I've found that taking a break to do some 1% Fusion runs seems to help be perform better on 100% single segments. My last 3 runs have all been sub 1 hour: 58:11, 58:27, and 59:27 (this one was last night...sucked hardcore).
Sometimes playing a different game for a little while will help :)
Sometimes playing a different game for a little while will help :)