It is extremely competitive. Stress is indeed motivational , and it is part of what makes it fun. Once the difficulty starts to increase I can spend an insane amount of time on a simple task. I stay away from these competitions, simply because I don't have time to dig into the material and it makes me feel terrible when I have to abandon a task because of real life, or xyz.

I do have tremendous amount of respect of the developers who completes these on the back of their hands.