Think of it using these hypothetical examples:
Good launch, you get full traction at 10' and go full power and traction for 1310 feet.
Bad launch, you get full traction at 50' and go full power and traction for 1270 feet.
Think those 40' are going to make much difference in the speed you reach at the end of the track? Not really, just a slight difference. But, it will take you significantly longer to go the full 1320 feet with the worse launch (mostly because it took you longer to get through the first 60').
