What's the one Shopify conversion change that surprised you the most?

Curious what's actually moved the needle for people here.

I've talked to merchants building with PopBoost, and the answers are always different. Some swear by exit intent popups. Others say the free shipping bar was their biggest AOV lift. A few said just showing real stock counts ("Only 4 left") changed everything.

What's yours? The single change that surprised you most with how much it moved conversions.