Table games are really hard to figure losses at especially when there are guys like me out there who "never win". I always squirrel chips away into my pockets as I win. It keeps any losses to a minimum and helps my player rating when I leave the table complaining about how much I lost.
Sure there are pit bosses and dealers who can accurately track that but most are too busy or lazy to do so. I even surprise myself by how many chips I have in my pocket when I hit a decent winning streak. Also if you know you are going to squirrel chips away you are less likely to worry about a large buy-in (which helps you player rating in some casinos also).