We rebuild the page closest to your sale and run it against your current page 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. Layout, copy and offer rebuilt as a whole, not a button colour.
Old page and new page live at the same time on your traffic, so seasonality and ad spend hit both equally. The result decides.
After the rebuild, a steady testing programme. Each test is written down, run to a clear answer, and kept or reverted on the number.
Fewer opinions, more tested changes: every claim on your store is settled by your own traffic.