I've wired a few electrical boxes, but always was curious; how much pushing is acceptable to attache the fixture into the box? I just finished wiring a GFCI into a 4 inch box with a raised cover, and 3 Romex cables entering the box. Not matter what I did, I had to push a bit to get the cover with the GFCI attached to it to close. Maybe the last 3/4 of an inch was pretty springy. The pros on Youtube make it look so easy and neat.