Self Checkout

having options is the key
i'd rather go through human checkout - but if there is one human checkout lane and 4 overflowing carts already lined up, it forces the issue
Trader Joe's usually has all 8-10 lines open and even when it's 3 carts deep, the lines move fairly quickly bc they know how to scan and bag
otoh whole foods will minimize as much as possible while still looking like they're accommodating (2-3 at best)
Winn Dixie will have one lane open no matter what

i think the rule of thumb should be open another lane when the other lanes get 3 carts deep

I prefer human checkout, especially at the grocery so I don't have to figure out produce.

Costco has self-checkout figured out pretty well, because it's well manned, but the key is let the customer use the scan gun, and that seems to come and go. I have been chastised for grabbing it a few times.