Here is my .02
Firstly, why are you going straight to sanding the tip ?? The tip should only get "sanded" when it is so hard it cannot be aerated with a tip pick. I will lightly scuff mine every 12 weeks or so. I don't "sand" it. By using a tip-pick,you can keep the tip breathing , hence it will hold chalk. I only scuff the tip (I guess you would sand it) when the tip needs to be reshaped or is so hard it won't open up with the tip pick.
I get 3 League seasons plus practice out of my tips which is about 18 months of wear.
Hope this helps :smile: