[bkrodgers]

Flashing does overwrite everything. It should not, in theory, be necessary to flash back to stock first. However, many people, myself included, have found that it put an end to problems we were having with random freezes and even hard resets we didn't ask for. I don't think anyone quite knows why flashing to stock seems to do a better job of clearing things up, but if it works, why ask why?

I don't think you have to do it every time. I've flashed a dozen times since I did it last and haven't had any problems with the random hard resets since. But if you're having problems, or if a chef recommends you do it for a certain release (like Mighty did on one of his awhile ago), I'd say give it a shot.