An electronic item with rechargeable batteries needs downtime to re-charge the batteries or else at some point the item shuts down.
The idea of vacation serves the same principles. Take some down time and recharge your batteries.
Its truly a shame that learning days are getting longer and longer and Bein Hazmanim gets shorter and shorter. Even teenage yeshiva boys need downtime to recharge their batteries. Burnout can be a terrible thing as witnessed by many threads posted here