My testing center was incredibly strict. I mean, if a girl had her hair in a pony tail, it had to stay in a pony tail the entire time. If she wanted it pulled back, she had to pull it back before entering the room. We were told that excessive face scratching/glasses adjusting would be considered suspicious.
We were also told that if we wore a sweatshirt in, it had to stay on the whole time. Watches had to be removed, no matter what. In other words, the way you enter is the way you stay...PERIOD. I thought it was great security though. I didn't mind.
I am not sure how the lockers are everywhere, but the lockers at my testing center were in the same room as the proctor, so everything was secure. She watched what we took in and out of lockers, so she could see if a cell phone was removed, I would guess. There were cameras everywhere, including by the lockers.