When you contact tech support one of the first steps is almost always to restart. Why? Because it is remarkably effective. It’s not a stall tactic or Hail Mary pass. It tends to work, it doesn't cost anything and it doesn't take long. Even if it doesn't immediately solve the problem your system will be left in a better state. Rebooting is almost always the best first step.
If restarting is a good remedy it is even better preventative medicine. Instead of waiting for problems to force you to restart you can avoid countless problems by choosing to restart on a daily basis.
Why does it work? We could talk about the second law of thermodynamics and how systems tend to move from a more ordered state to a less ordered state. We could talk about renegade processes, memory leaks, maintenance routines and how a reboot restores your system to an ordered state. Or you can just do it – it’s best maintenance you can do and it’s free.
Not good enough? Rebooting flushes your RAM and frees up memory that may not have been released to the system. It also deletes countless temporary files created by various applications. All of this makes more resources available to the system. Many operating systems have maintenance routines and update processes that are triggered by a reboot.
What about servers that runs for months, sometimes years, at a time? That is a very different thing! Typically a true server does very few things. Different users are not signing in and out, using different applications and downloading files. Instead servers get to focus on a very specific job in optimized conditions.
Every day is best. Sure – you could probably do it every second or third day but that makes it far to easy to forget. “Did I do it last night? I can’t remember – I’ll wait and do it tomorrow”. Before you know it weeks have slipped by. I can't tell you how many times I have talked to users that, when asked when they last rebooted, insisted that "if it wasn't yesterday it was definitely the day before" only to see in their logs that it had been much, much longer.
Making it part of your daily routine just works better – if it is the first thing you do each day or the last thing you do each night you won't forget.