I switched from Petzilla/Lizard litter a while ago, and now run Harbor Freight's crushed walnut sandblast media (comes in a box/1-ft cube). The pet store stuff w/ a tablespoon of paint thinner/dryer sheet worked great, but was
just small enough for me to have to poke it out of the flashhole with a paperclip. No big deal -- just an extra step.
The Harbor Freight media is
just that much larger that it doesn't stick in the flashhole. When it's ground itself down to where it does, time to change.
Since I just dump things into the tumbler and leave it overnight (if not for days
!)that can be 300 hours for me.