Really depends on how good the self checkout is. Usually local chains have great self checkout and the foreign chains I’ve tried were terrible and annoying. If I use a shopping cart I always use the cashier as you’re supposed to. In convenience stores I prefer the cashier but I use the self checkout when there’s already someone else at the cashier (usually everyone else avoids the self checkout in convenience stores in my experience, so it’s always free immediately even when there’s long queues at the cashier).

I haven’t really encountered self checkout in other stores than grocery and a single convenience store chain though, so can’t comment on other types of stores.