Pool chalk is not the most efficient accessory in the poolroom. Over the years I've generally been spoiled to the extent that I throw away pieces of Master chalk when they get to the point that many people think it is just getting broken in, and have pretty much done that for all the Master chalk used in our 10 table poolroom for 20+ years. I've always thought it was a waste in that you're throwing away the cube of chalk when you've likely used no more than 20% of the total chalk in the cube.
Recently, just for the heck of it, I've gotten in the habit of sanding used pieces of chalk down (simply flipped upsidedown) on a piece of 60 grit sandpaper on a flat surface. If you're doing a bunch of pieces, it can make a mess, so it's advised to do it outside on a table. After sanding it the necessary amount, you basically have a new looking piece of chalk - just a little shorter. I can do this a few times per piece, until the side of the chalk goes from 7/8" down to about 1/2". You could go even further, but the paper wrapper usually is about worn out by that time, and it seems a little extreme to go any further than that.
Another factor is that a growing number of the regular players and weekly tournament players in here, including myself, use their personal chalk these days, so most of the players using the shorter cubes of Master are the recreational players, whom quite likely don't care and may not even realize they're playing with recycled chalk.
As a result, instead of going through a gross box (144 pieces) of Master blue chalk about every 2 months, now I can get close to 6 months out of a box. The roughly $100 in savings per year is irrelevant in the big picture, but it makes me feel better about not wasting perfectly good chalk. Just curious how others here would view a poolroom owner/manager who does this?