I suppose it goes without saying that a real AP would never miscalculate their chips, but I can attest that an AP wannabe can get so caught up in count, cover, talk, etc. that they discover they are up 120 units when coloring up after three hours of play. From comments I've seen here, 20-30 units would be a reasonable level to cap off if you want to continue playing at a particular casino, particularly if it is smallish. Note to self- stacks of four green chips are worth $100, not $25.