They all stay at the same check points

Why does Will push him self so hard, barely sleep and only eat fruit cake to cut down on his weight if they all end up at the same check points every night.

Each morning they show him starting out before anyone else with only a few hours sleep yet they all (he and his main competitors) seem to end up in the same camp each night. His extra effort doesn't seem to put him any further ahead in the race.

Can someone explain this to me