I'll only hit driver off the tee on a par 5 if I have a shot at it in two. If its going to be a 3 shot hole, then I just hit a hybrid or a 3 wood off the tee. I think I read a study once that the scoring average on the PGA tour for laying up on par 5's and going for it was withing 0.1 That should tell you what you need to know.