2_i 

I think psychologically it is difficult to go to the other side, but of course it is principally possible. You begin to destroy the threads then and shards of metal begin to come off. Yes, it begins to be loose then too, but the usual owner doing maintenance would not go there. The way you can test where you are is to ride and listen to the squeaking, while carrying a wrench. Then you tighten a bit more and listen do the squeaking. If yes, you are likely on the right track. Presumably a chainring that was removed and not put back tightly enough could generate a squeaking too. In that case the squeaking would depend on the ring you were on. Note that that legs can generate far greater forces than hands can. What might seem tight for the hands, might not be such for the legs.