An ecommerce business with a feed has two ways of advertising products: standard Shopping (control by product group, Shopping only) and PMax with a feed (full automation, every network). They can coexist, but under one rule that conditions everything and that a lot of people don't know about.
The rule: PMax always wins
If the same product is in a standard Shopping campaign and in a PMax campaign in the same account, PMax has priority: PMax plays the auction, regardless of bids, targets or the standard campaign's priority. The consequences:
- A "whole catalogue" PMax campaign empties your standard campaigns without warning: they drop to residual impressions.
- You cannot use campaign priority (module 5 of the Intermediate level) to share traffic between PMax and standard; only between standard campaigns.
- For a product to be in a standard campaign, it must not be in any PMax campaign (exclude it from the PMax product listing).
When each one suits you
| Standard Shopping | PMax with a feed | |
|---|---|---|
| Control | By product group, bids/targets by margin, full negatives | Signals, limited exclusions, one goal per campaign |
| Reach | Shopping only (and Search with listings) | Shopping + Search + Display + YouTube + Discover + Gmail |
| Reporting | Complete by product and term | Partial (lesson 3) |
| Performs better when | Margins vary a lot, a catalogue that needs fine-grained exclusions, a team that manages it | Clean value measurement, volume, homogeneous catalogue, creatives for the other networks |
| Risk | Lower reach | Opaque split, brand inside, junk placements |
The three structures
1. Standard only
Total control; you lose the visual networks. For catalogues with very different margins, small accounts or teams that want to manage things hands-on.
2. PMax only
One or several PMax campaigns with a feed, by family or by margin (each with its own target ROAS). Maximum reach; control through exclusions. For accounts with clean value measurement and volume.
3. Hybrid (the most common in mature accounts)
- By margin: PMax for the high-margin products (where the extra reach pays off) and standard for the low-margin ones with a demanding target ROAS and fine-grained control… or the other way round, depending on where you want the control.
- By stage: new arrivals and products with no history in standard (to accumulate data with control) and the stars in PMax.
- By intent: a brand standard campaign with priority, and PMax with brand exclusions for everything else.
The technical key to the hybrid structure: disjoint product listings (by custom label or category) between PMax and standard, so that the "PMax wins" rule doesn't empty the standard campaign.
Moving products from one to the other
- Label (custom_label) the set that is moving.
- Add it to the destination campaign's product listing and remove it from the source campaign on the same day.
- Budget and target in line with that set (don't inherit the ROAS of the whole catalogue).
- Two to three weeks of learning; compare with the previous performance of the same set (the same weeks of the previous year if there is seasonality).
Really comparing PMax and standard
The honest comparison is not "PMax ROAS vs standard ROAS": PMax includes brand (if you didn't exclude it), view-through conversions and different networks. The methods:
- Google's official experiment: standard vs PMax on the same set of products, traffic split, several weeks. That is the clean comparison.
- Same set, alternating periods (4 weeks standard, 4 weeks PMax) with a seasonal adjustment: less clean, acceptable.
- Always with brand exclusions in PMax, click-through conversions, and looking at the account total (are sales going up, or just moving around?).
Typical mistakes
- Launching a PMax campaign "with everything" and not understanding why the standard one died.
- Comparing aggregate ROAS.
- Moving the whole catalogue to PMax with a single target ROAS: the low-margin products take the budget.
- Not excluding brand in PMax and concluding that PMax is better.
💡 Ninja trick: Shopping Ninja analyses products wherever they are (standard or PMax), because it reads performance by feed product, not by campaign. Its POAS traffic light per product is the basis for deciding the hybrid structure: the reds out of PMax (or out of everything), the greens where they get the most reach, and the margin label as the border between campaigns.
What you should remember
- PMax always wins over standard Shopping for the same product: disjoint listings, or the standard campaign dies.
- Standard = control; PMax = reach. The hybrid by margin or stage is usually the mature answer.
- Move products by label, on the same day, with their own target.
- Compare with an experiment, brand exclusions, click-through conversions and an eye on the total.