How much sanding do you need to do to them when they are new and how often to sand them after?
I sand mine back and forth in the area I'll play on just enough to build some good ridges. Then I'll wipe away ALL of the dust with a cloth. That way, the ridges can't fill in with glass dust as I play and I don't have to recondition all that often. That said, some calls seem to play a little better with the dust left on.