I'm from NJ where we ONLY have full serve. I've never seen anyone pull forward after they've been filled up, although if you pay by CC, they do that before they start fueling, to make sure the card is valid, so when they're done all that needs to be done is pull the nozzle out, put your gas cap on, and return your card and receipt to you. Which takes about 3 seconds.
I normally pay with cash, so same thing, only they close up my cap, and i hand over the cash. If they need to give me change they do, but again, it takes very little time for that as well.
At least here, since its full serve only, most people know to wait until the car ahead of you is completely finished, and paid.
My issue however, is people who pay, start their car, and sit there, checking their phone, putting lipstick on, etc. when I'm waiting to pull up to the pump! but that's a whole other thread.