I've been trying to figure out how often one needs to rehair a bow, and the answer I seem to see is "periodically." What does periodically mean, every few months, once a year? Anyway, I've had my bow for about a year and half so I'm thinking that it's probably time to rehair it, but I was curious in general. I generally play from an hour and half to three hours a day and spend about a third of my time bowing, more recently. At this rate how often is a general rule?