Where taking a break from a difficult and unsolved problem allows the mind to process it unconsciously. That is why thoughts occur when in the shower or during sleep times where the default mode network of humans activates. It helps to overcome mental overload and the feeling of dread of suddenly having performance lowered compared to normal. Well, it can certainly help. This is also probably a reason for the "study hack" of interleaving, and also helps prevent fatigue! That's why sleep is good. Even school does it. Finally one good thing (that does not make up for all its bad)