We rebuild the page closest to your sale and run it against the one you have now, on your own live traffic. The scoreboard is revenue per visitor, not a dashboard metric.
Usually the product page, because that is where the money is decided. One page, rebuilt properly, rather than a list of opinions about the whole store.
Old page and new page run at the same time on your own traffic, so seasonality and ad spend hit both equally. The result decides.
Two or three tests a month after the rebuild, each one run the same way and reported on revenue per visitor.
Fewer opinions, more tested changes: if a rebuild does not lift revenue per visitor, it does not ship.