Like I mentioned, you don't have to reset if you don't want to. You could do it after update and when you encounter problems. Last time when I upgraded from 2.3.3 to 2.3.6, I had reboot issues. It didn't happen all the time, but the good news was that it resolved itself after a few weeks of use.
Some are not so lucky and had many problems. Like I said, if the OP is willing to do it, then by all means do. But if not, then just flash first and see how it turns out.