You need the disc ONCE. I have a few GC games and with the exception of TWO and a Half, they all work flawlessy. I don't have to switch discs, I don't have to worry about my drive breaking one day, I don't need a memory card and I don't have to worry about my discs one day being scratched, because the verification process is only needed once.
So no, it is NOT useless, it is a very handy tool that works quite well if you set it up right. And while I think that tueidj may sometimes sound a little off putting to some (i personally dont mind) it is perfectly understandable that he is pissed of with people complaining about his work methods when he is doing a FREE service FOR YOU. You should be thankful he does what he does instead of complaining about things that you dislike.