Even/Negative splits are ideal, we all know this. Now, has anyone gone out conservative only to find out they couldn't really change gears in the second half? Is it possible to get into a rythm and kinda get 'stuck' or experience some problems that would have happend to equal extent regardless of if you had gone out say 2min faster at the half giving you a 2min cushion. What is your marathon racing strategy/advice/experience you can offer to a newby at the distance? Thanks!