when they reload where as I tend to just do the push/pull method. Is one way better than the other?
The guy who is very probably "the" AR guru currently teaching is Pat Rogers. He is an advocate of the push-pull. IME, especially if you are using issued magazines, slapping is both wasted motion and if you have a weak magazine, it may be enough to dislodge some rounds giving you a lovely malfunction.
FWIW, I've seen the "failure to seat" problem enough that push/pull is my advice.