i think that it depends on what kind of running play and result that you want (sometimes it's good to just gain a couple of yards). at times, i'll try and open up a hole, like you are saying, and run through the line. sometimes i'll slant all of my o-linemen one direction and run that way, sometimes i'll set up that way but run the opposite direction with a guard being pulled, a bit of a counter. i guess that it all depends on where the strength of your o-line is, and using it to your advantage. and, a little bit of luck never hurt anything either!
