How often should I reboot or restart my computer?
There is no minimum or maximum amount of times a computer should be restarted. Unless your computer is requesting that it be restarted or that it needs to reboot leaving your computer on without restarting will not harm the computer in anyway.
In addition to restarting or rebooting the computer when prompted it's also a good troubleshooting step to restart your computer if it is experiencing issues that cannot be resolved. Often restarting the computer will fix many abnormal issues.