The MC has the power to set a checkpoint at any point and he can return to that checkpoint whenever he wants. The only caveat is that the checkpoint gets erased when he falls asleep. So the rational thing to do would be to set a new checkpoint whenever he wakes up and to not touch that checkpoint ever again, right?

The weakness of checkpoint ability users is that they can get stuck in a "death loop". If they ever set their checkpoint after a "point of no return" then they become trapped in the death loop. Simplest example is someone who sets a checkpoint after they get pushed off of a tall building. Every time they reset, they're in the middle of free fall. So they're trapped in the falling loop, they can't get any further than that.

The logical thing to do, therefore, would be to set your checkpoint as early as possible so that you don't get trapped in one of those death loops. Since the MC's checkpoints get erased by sleep, then it's logical for him to set his checkpoint first thing he wakes up. But for some reason he doesn't do this. He only gets one checkpoint, and he continually sets it whenever he wins a gamble.

Over 18 chapters he went through multiple life-or-death scenarios where his decisions to move the checkpoints forward have left him with fewer and fewer options. He never learns this lesson. It's the first thing I thought of when he explained his ability and yet the MC for some reason doesn't do this. It's just stupid.