I think bringing the cart to the corral is the bare minimum, and generally people will try to get away with the minimum for most tasks and social obligations. If you don't at least bring it to the corral you're deranged, but beyond that I'd rather a job is done half-assed than not at all.

If I get to the corral and there's two or three loose carts I'll stack them with mine. If there's six or seven I won't fix them all but I'll still be as neat as I can.

If the store has different sized carts, this is always a bigger problem. People generally are uncoordinated at figuring that out.

My grocer has one of those schemes where the carts are unlocked by putting a coin in them, and you get the coin back when you return the cart. It works pretty well for keeping things tidy.