Confusion

Well it seems to have happened again. I have managed to confuse myself not by misunderstanding the issue at hand, but rather by trying to apply knowledge that doesn't come into play until later.
Apparently I have problems with doing the minimum thinking required. I had trouble understanding some of the cases which we were discussing today. When I was reading them I had all sorts of 'what ifs' pop into my head. It seemed the case had so many things it could hinge on and yet the professor seemed oblivious. Oh but not oblivious. Another student asked a question I had been pondering, one about why something had not been considered. This other student was told that she was getting far ahead in the course and not to worry about such things.
Relief? Sort of. How do I know what to not worry about and what is a legitimate 'gotcha' of the lesson? I blame my wandering mind. If I didn't go off into woods and pick up random leaves and stones perhaps I wouldn't get ahead of myself. Instead I go off wandering and see something up ahead only to me it seems more off to the side and I try to evaluate it only to find out, no! The path is curved and what appears to me to be off to the side and part of the here and now is really further ahead and not worth my thought until I get there.
Bugger you crazed wandering mind.