Depending on just how slowly the prop moves while I'm in the zen-like process of prop balancing, this is normally where I quit, whether it's the blades that I'm working on (sanding the heavy side - starting with 80 grit and finishing with 320 - from the back) or the hub/hole position (by adding CyA sped up with kicker to the high side). While I used to take the balancing to the Nth degree, I have found that a very slowly rotating prop is not an issue worth worrying about.