We rebuild the page closest to your sale and run it against your current one 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 done properly rather than a list of small opinions.
Your visitors split between the new page and the one you have now. Old and new run at the same time, so seasonality and ad spend hit both equally.
After the rebuild, two or three tests a month against the pages that carry the most revenue. Each one decided by the result, not the debate.
Fewer opinions, more tested changes: every claim on your store is settled by your own traffic.