Variants are the whole game
A single style in six sizes and four colours is twenty-four feed entries. Grouped badly, they compete against each other in the same auction and split your conversion data twenty-four ways, so nothing ever accumulates enough signal to bid on.
Correct item_group_id grouping, with size and colour in the title, is the fix — and it is usually worth more than any campaign restructure.
Returns change your maths
ROAS in the interface is reported on revenue, before returns. A 30% return rate turns a 3x into something closer to 2.1x, and you paid the ad cost on the returned order too. Work it out with returns included.
The calendar moves before the weather
Demand shifts weeks ahead of the season. Budgets planned on last month always lag, which is why fashion accounts feel like they are permanently catching up.
More on the vertical: Google Ads for fashion.