I think the trick with the 3 peaks is to be able to run all the way up pen y ghent, without pushing too hard but not walking either, and being willing and able to try and run the couple of plateau-ey bits* going up Whernside and all of the slabbed path up Ingleborough to the steep final ascent. If you can somehow pace yourself to do all that, you'll have a good day.

* Okay to call them plateau-ey is a slight overstatement . Not stupidly steep bits I mean