For the people who are fast or in a rush it can absolutely be faster, but for people who take their time it can also be a lot slower (old people that stretch everytime they get out of the car, people leaving their car at the pump to go in and get smokes, people hogging the pump while they finish reading/texting something, airheads who have no idea other people are waiting on them etc). It might not be a lot, but it adds up quick. All it takes is a couple slow people and half the station is bottlenecked. I live in PA now and see people do this all the time, but it still tends to be faster than NJ because there's so many pumps you're never waiting on anyone else.

I live in PA now and prefer pumping my own gas but we also have giant Sheetz/Wawa's on every corner with like a minimum of 12 pumps at each. A lot of the NJ gas stations I remember growing up were smaller 4 pump stations. With the amount of people compared to the size of the stations, I feel like they'd get jammed up pretty fast. Especially with assholes who are done filling up but sit there hogging the pump while they text or go inside to take a dump or something. At least with attendants they can ask people to move and help maintain flow of traffic. I think NJ stations would need to be bigger for it to be practical there.