Back when I was collecting I would often get bows tillered one way or the other, and at different periods I shot both ways. I never worried about it, just raised the nock if it was tillered split and I was shooting 3 under, or vice versa. I never found it that critical. A year or so ago I built a set of bows that tillered negative, neutral and positive and shot them all both ways. It affected the tuning, but not really the overall performance of the bow that I could see. Of course, I didn't make the Olympic team, either....