Performance Max campaigns can be a winning option for eCommerce. 

But - here’s where most people go wrong - PMax will not do the heavy lifting for you.

Most marketers understand that Google’s AI and Machine Learning are at the forefront of PMax campaigns - and therefore, that means less time, less effort, and less thought is needed on their part, right?

Unfortunately, this is pretty far from the truth. 

When it comes to eCommerce, PMax needs to be treated like a Formula 1 car - powerful when tuned correctly, but arguably the fastest way to lose money if you don’t know what you’re doing - or have the right setup to support it.

In order to help eCommerce marketers get better results from their PMax campaigns, we spoke to Kirk Williams about how to turn underperforming PMax setups into high-performing ROI machines.

Kirk is the founder of ZATO Marketing, a notable TEDx speaker, and 2025’s 3rd most influential PPC expert according to PPCSurvey. With years of experience optimizing successful campaigns for brands like Traeger Grills, Ridge Wallets, and Coober Footwear, Kirk had a wealth of knowledge, insights, and experience to share about:

• PMax campaign structure
• Feed optimisation
• Scaling strategies
• Overcoming the PMax “black box”
• Practical tools to unlock more insights
• And much more

Watch the full session here, or keep reading for the written breakdown:

Timestamps:

0:00 - Intro

3:55 - How PMax differs from other campaign types

6:29 - PMax campaign structures for shopify stores

13:57 - Feed optimization best practices

19:33 - How to get more insights from PMax

22:01 - Driving the most revenue from PMax

26:54 - Final thoughts

Understanding what PMax really is (and what it isn’t)

While many marketers think of PMax as a potential growth engine, Kirk believes it’s essential to recognise its true role:

“PMax at its core is like a catfish-it’s a bottom feeder. It cleans up the stuff at the bottom of the funnel. Too many people are asking the catfish to swim for the open ocean and scale it, and it’s just not going to happen.”

In other words, PMax excels at capturing demand that already exists - particularly lower-funnel, high-intent audiences. But if you’re expecting PMax alone to drive rapid brand growth or acquisition of new customers, you’ll be disappointed.

PMax is essentially a combination of all the main Google Ads channels:

• Shopping Ads (the core channel, inherited from Smart Shopping)
• Search Ads
• YouTube
• Display (GDN)
• Discovery

However, unlike Search campaigns, you can’t directly target keywords in PMax. It’s a feed-based system where your product data plays a central role. The feed powers which products are shown to which audiences, across Google’s entire ecosystem.

Kirk summarised:

“Google sells PMax as the easy button. And in some ways it is easy to set up. But figuring out what’s ideal for an account can actually take time, testing, and budget.”

How to structure PMax campaigns for eCommerce

When it comes to campaign structure, Kirk dropped a refreshingly honest take: 

“There are no “universal best practices” for PMax. What works for one account might flop for another. We’ve seen every possible tactic work and not work, depending on the account. So there are literally zero best practices in PMax.”

That said, Kirk and his team have a few notable core principles that are likely to lead to significant performance improvements for most accounts:

1. Segment your top products

Most eCommerce stores follow the classic 80/20 rule - where a small group of products usually drives the majority of revenue. In many cases, 10 to 25 SKUs will account for 70–80% of sales.

That’s why one of Kirk’s key recommendations is to break out these hero products into their own dedicated campaigns:

“Identify the top products driving 70–80% of your sales. Then ensure they’re in their own campaigns, with their own budgets and ROAS targets. This gives them the attention and control they need.”

When these products are mixed in with lower performers, Google’s algorithm might not allocate budget in the most efficient way. But when they’re in a focused campaign, you can:

• Assign a dedicated budget
• Apply appropriate ROAS targets
• Test different creatives and feed optimisations
• Ensure they consistently get visibility and scale

It’s a simple but highly effective way to get more revenue out of your best-performing products.

2. Avoid a single “catch-all” campaign

It’s tempting to throw your entire product catalogue into one big PMax campaign and hope the algorithm figures it out. While simpler, this usually leads to uneven performance:

• Google will naturally favour products that already convert well, while others may barely get any impressions.
• “Zombie” products that don’t get shown might still be valuable, but they never get a chance to prove it.
• Without segmentation, you lose control over budget allocation, ROAS targets, and optimisation levers.

Instead, segment your campaigns in a way that gives you better visibility and flexibility. Useful segmentation strategies include:

• Sales tiers: Top sellers vs. mid-tier vs. long-tail products
• Seasonality: Break out products that sell strongly in specific seasons
• Product categories: Group similar products together for more relevant targeting and creative
• New vs. evergreen: Prioritise visibility for newly launched products

This allows you to manage budgets more strategically and gives under-served products room to grow.

3. Leverage the “hero, zombie, villain” segmentation model

Kirk also highlighted the increasingly popular segmentation strategy promoted by PPC expert Miles McNair - the “hero, zombie, villain” model.

Here’s how it works:

• Hero products: Top-selling products with strong performance and reliable ROAS. These deserve a focused budget and separate optimisation.
• Zombie products: Products that currently receive little or no visibility but may still have potential. These often need testing, improved feed data, or creative experimentation.
• Villain products: Products that attract lots of clicks but few conversions, wasting spend. These should either be fixed (if possible) or deprioritised.

We’ll admit, the framework does sound like something from a bad movie script. But it’s arguably the best way to structure PMax accounts:

“It’s a great way to structure your Performance Max strategy because it lets you focus budget on proven winners, identify and revive under-performing products, and limit waste on poor-converting SKUs.”

In short - it helps bring more clarity and intentionality to your PMax structure. And the more granular control you have, the easier it is to steer campaigns towards profitable outcomes.

Feed optimisation: The foundation for PMax success

Because PMax relies so heavily on your product feed, feed optimisation is one of the highest-leverage activities you can do.

“If 95% of brands simply optimised their titles properly, they’d see a huge jump in performance.”

Here are Kirk’s top feed optimisation priorities:

1. Product titles matter… a lot

Your product title is the most important element in your feed. Kirk recommends:

• Putting key attributes at the front of the title (e.g. brand, product type, key features)
• Aligning titles with how people search-not internal SKU codes
• Avoiding clutter or irrelevant terms

Example: Instead of “SKU 1234 | BrandName | Blue”, a better title would be:

 “BrandName Blue Ceramic Coffee Mug 16oz”

2. Optimise product descriptions

Kirk suggests using tools like ChatGPT to improve descriptions - but, as Fred Vallaeys mentioned in a previous episode of the Paid Media Lab - always review thoroughly and verify accuracy. 

When it comes to prompts, include as much information in the brief as possible. Start with:

• Target audience
• Key product features
• Customer reviews
• Word/character limits for Google Shopping

Optimised descriptions improve relevance and can significantly impact CTR.

3. Use custom labels strategically

Custom labels are a powerful but underused feed feature. You can use them to:

• Segment products by seasonality (e.g. Spring Collection)
• Tag new products for launch campaigns
• Group by margin tier (though Kirk isn’t a huge fan of margin-based segmentation)

Example: For a drinkware brand with loyal customers seeking new designs, create a label for “New Arrivals” and run a dedicated campaign targeting past purchasers.

4. Understand the role of pricing

Price is a critical - but often overlooked - feed factor.

“If you’re selling a product for $25 but everyone else is at $21.99, no one’s going to buy from you. They’ll click, but not convert-which wastes budget.”

While PPC managers can’t always control price, being aware of price competitiveness is vital for managing campaign expectations and performance.

Dealing with the PMax “black box”

One of the most common frustrations with PMax is its relative lack of transparency compared to traditional campaign types.

It’s long been considered a ‘black box’ campaign type - creatives go in, “something” happens, results come out. And unless you’re a senior Google employee, you’ll likely never know what that “something” is.

While Google has made improvements in recent months - such as better reporting on search terms, placements, and the ability to add negative keywords - PMax is still far from transparent.

To help overcome this, Kirk recommends supplementing with third-party tools and scripts, such as:

PMax Scripts:

PMax scripts are incredibly useful for surfacing some of the data and insights that Google’s black box likes to hide.

Various script banks exist - such as this one from Marc Cornelus - that are a treasure trove for marketers looking to get more from their PMax campaigns. 

(Note: not all of these scripts are specifically designed for PMax campaigns. Pick and choose the ones that are most useful for you.)

We’ve also just updated our own list of Google Ads Scripts to help marketers stay on top of their campaigns. So, take advantage of the free scripts that are available to marketers, and use them to make smarter, more informed decisions. 

Optmyzr

Zato Marketing also uses Optmyzr, a paid tool that:

• Provides advanced reporting
• Surfaces data not easily accessible via the Google Ads UI
• Helps visualise PMax performance more clearly

Kirk emphasised that PMax tools don’t give you everything, but they help marketers make more informed decisions and avoid running PMax campaigns blindly.

How to scale PMax campaigns effectively

A key question asked in the session was: If you have a solid-performing PMax campaign and want to scale, what should you do?

Kirk’s answer was probably not what everyone wanted to hear - but something that’s critical for marketers to understand:

“There are limitations to how much you can optimize PMax. Too many people are obsessed with trying to make PMax do what it can’t do.”

After you’ve optimised your feed, structured campaigns well, and tuned ROAS and budget, you will hit a plateau.

Beyond that point, scaling requires looking outside of PMax:

1. Drive more demand externally

“PMax will grow with your brand - but it won’t scale your brand by itself.”

To fuel sustainable growth:

• Invest in top-of-funnel channels (Meta, YouTube, influencers)
• Improve creative assets (video, imagery, landing pages)
• Test and refine offers and messaging
• Build brand awareness so more users enter Google’s ecosystem searching for your products

2. Understand PMax’s role in your funnel

Kirk explained that PMax is not a demand generator-it captures demand. If your brand isn’t growing awareness externally, PMax won’t suddenly find new audiences.

“You can only increase budget and decrease ROAS targets so many times. After that, scaling has to come from external demand generation.”

Final takeaways

To summarise Kirk’s advice, here’s a checklist for driving better eCommerce results with PMax:

• Understand PMax’s role: It’s a bottom-funnel, demand-capturing tool. Don’t expect it to scale your brand alone.
• Structure campaigns strategically: Segment hero products and avoid bloated “catch-all” campaigns.
• Optimise your feed: Focus on titles, descriptions, custom labels, and pricing.
• Supplement with third-party tools: Scripts and platforms like Optimizer can surface valuable insights.
• Scale externally: Invest in top-of-funnel marketing to drive demand, which PMax can then efficiently convert.
  
  

As Kirk put it:

“It’s a fairly basic business principle, but I don’t hear it enough. You need to scale outside of PMax first, then PMax will scale with that demand.”

If you want more expert insights on optimising your paid media efforts, head over to lunio.ai/resources.

And if you found this session helpful, be sure to subscribe to the Paid Media Lab so you never miss future episodes.