I'm kinda confused because you start out saying it's obvious that you should look at the CB last, but then go on to say you look at the OB last in competition, which is when it counts.
I've already gone in to great detail in previous posts about the comparison to other sports, and why you don't have to focus on the cue ball even though that's what you are directly contacting. I won't repeat myself, but you can read post #52 in this thread, like 6 posts up.
If you look at the object ball last during competition, then you agree that's the correct thing to do. Sure you will do different things in practice, such as focus on your stroke and mechanics, but to actually perform the best when it counts, you aren't thinking about any of that stuff, and you're looking at the object ball last.
I hope you aren't looking at the cue ball last every time you practice, because then you are developing habits that are different than what you are doing in competition. You should only need to look at the cue ball last in practice when you are trying to correct something that's wrong with your stroke, or your contact with the cue ball.