Volume Dressed as Efficiency

Source: Mike Ryan / SMEC (Smarter Ecommerce), Search Engine Journal — link

Google's pitch for AI Max: 14% more conversions at "similar efficiency." That claim has been floating around since launch with no independent ecommerce data to check it against.

Now there is.

Mike Ryan at SMEC analyzed 250+ Search campaigns running AI Max. The revenue number checks out. The efficiency number doesn't.

SMEC's dataset covers ecommerce accounts. Google's 14% benchmark came from non-retail campaigns. Nobody had published what happens when you flip AI Max on in a shopping-heavy account.

The numbers:

• +13% median conversion value (close to Google's 14% claim)
• +16% median CPA (Google never mentioned this part)

The revenue lift is real. But each incremental conversion costs more than your baseline keyword traffic.

If you've suspected that automation grows volume at the expense of efficiency, this is your confirmation.

AI Max finds queries your curated keyword set misses. Those queries convert. They just convert at a worse rate.

Ginny Marvin, Google's Ads Liaison, acknowledged this pattern. Incremental volume follows diminishing returns.

The next marginal conversion always costs more than the first.

Nearly 50% of advertisers testing AI Max are also running DSA and Performance Max at the same time.

Three expansion layers competing for the same queries. That fragments your conversion data across campaigns and slows down how Smart Bidding learns.

• 1 in 6 accounts: AI Max + DSA
• 1 in 4 accounts: AI Max + PMax
• Nearly half: all three stacked

Google says ad rank sorts it out. In practice, you lose visibility into which layer is actually driving results.

AI Max works. It's a volume expansion layer, not an efficiency optimizer.

If your account has headroom and you can absorb a 16% CPA increase for 13% more revenue, the math might work. If you're already tight on margins, this is an expensive way to find out.

The bigger risk is stacking. If you're running AI Max alongside DSA and PMax without auditing overlap, you're paying three systems to bid against each other on queries you already own.

Pull your Search campaign report for the last 30 days. Check if you're running AI Max, DSA, and PMax simultaneously. If all three are active, pause one expansion layer for two weeks and compare CPA.

Start with DSA... AI Max is designed to replace it anyway.