In my experience there is really no correlation that one station is better than another, it is more just the individual GA.

Also, there is pressure and actually awards for the employees for getting the planes off on time so I think they would rather just get everyone on. Of course, if you start boarding when you should there should still be about 10-15 mins before the door closes after the vast majority of travels have boarded. So it would be nice if they took the time to actually enforce the rules and still maintain a timely schedule.