Most computers need to go thru the actual shutdown and startup procedure occasionally.
Some Windows updates will require you to actually turn off (shutdown) and then start the computer for the setting changes to take affect. Windows will normally tell you when that needs doing.
Other times fully shutting down the machine will clear all areas where information is kept and sometimes clears a problem or makes the machine work better as space in memory and hard drive becomes available again
Servers (larger computers for groups) have been known to run for years without being shutdown and started however servers I work with I like to restart them about once a year to fully clear memory etc.
Restarting as opposed to shutting down and starting just stops Windows and other programs but does not remove electricity and occasionally fully de-energizing I see helps.
I would only suggest shutting down and starting just for that purpose of once or twice a year. However most of us turn them off and on more often a year due to moving machines, power outages, and to protect in electrical storms. If I am not going to use the machine a day or more I shut my PC down.