And if so, how often do you do it?
About once a month I check the processes that are running fully and Google any I don't recognise so I can find out what they do, where they are from, and if they are needed.
I also check the Windows services to see what has started straight after booting the system. And set any that are not needed from Auto to Manual.
Usually I like a system to be running less than 30 processes after it has finished booting. On my current main PC I have 28 processes running (if I deduct the Task Manager process), and if I shut down the extra ones I use (ultramon - 2 processes, Soundman - 1 process, Autodesk license - 1 process) it would drop to 24, or maybe less as some of the svchost instances might then not be needed.
It is important to occasionally check the processes that are running as this is a very quick way to discover if you have a trojan or spyware running on your system.
So how many processes are running on your system?