An explanation to NOT push preflop..

[Gramps]

If you insta-push any time someone completes at the later levels, people figure it out and adjust (he pushed, he effectively hasn't looked at his cards yet/I'm pissed off at this aggro biatch, I'm making a stand). A better strategy is to pass it up when you don't need it so much, and save that play for when those chips are very valuable (and you have some "stealing street cred."). I hear people say sometimes on this forum that your image doesn't matter in these things, but in SB vs. BB play it does IME - people remember how you've played them (at least in that particular SNG), and will make pissed-off calls if you keep running them over (often unknowningly making a proper calling adjustment to their opponent's unchecked aggression).