Most modern day computers and mobile devices have a limit. You’ll know when you’ve hit it when things start running slowly, battery life drains fast, things just don’t work the way they should. You try everything, then pick up the phone and call for tech support–they always recommend a restart.
A mental restart sets things back to normal. It clears extra memory baggage and dismisses extraneous code that causes things to bog down. It returns important settings that balance your machine to default status. POOF! The restarted device seems to have a new lease on life. It just works better.