It is unimportant how much you cant the bow on the range. It is useful to be able to cant the bow different amounts when you hunt, so you can deal with brush, etc, that might prevent a straight up and down shot. The most important thing is to maintain good form, rotating your string wrist to match the cant of the bow, so you don't torque the string. Some people can cant the bow all the way from straight up and down to sideways, which might be useful if you're shooting from under a low hanging tree or something. It's a skill worth practicing, just like shooting sitting down, kneeling, or at different angles other than square to the target, since we probably won't get a chance to set ourselves up exactly the way we would like when we're hunting.
I missed my one chance at a deer this year because I was sitting on a stool underneath a live oak tree, and when the deer got into position he was square in front of me. If I had shifted my shoulders around to get in a better shooting position, he would have been gone (which he was anyway after I shot over his back). So guess what I'm going to practice!
First things first, of course. Learn to shoot good groups with perfect form, and then you can start practicing the other stuff. In my opinion, perfect instinctive form means shooting at your "natural" cant, whatever that is, and I wouldn't listen to anyone else. I guess I could have saved time if I had started with that, huh!