Thinking once is okay for the same problem

I have a bad habit of repeating a same thought again and again, this is not useful when the problem is not worth thinking on and on.

The problem might be caused by some type of mental fatigue. When my mind is tired, I tend to react more illogically and become less considerate, and the repeating of one "satisfying" thought may help relieve the fatigue.

So, the final solution would be: try to schedule my time carefully, don't try to be perfect when executing and get to sleep as early as possible.