I marked 100, but I don't normally do them in batches. I keep my high volume brass in coffee cans (i.e. 9mm, 45acp, 30 carbine, 223.) In the winter, when the weather is bad, I'll prep cases when I'm bored, and store the primed cases together. When all my brass of a certain caliber is prepped, I'll load until I get tired, put everything up, and quit for the time being. This might be at 50 or 300 rounds depending on my mood.
For high power rifle rounds, I'll usually load 20 at a time. For revolver rounds, usually either 50 or 100 at a time. These are stored in ammo boxes.
For load development, I'll usually load 5 at a time.