Adding onto what Casey said, a ":heavy" workload for a reliever is about 100 innings, most go about 60-80 innings. Fro a starter, 175-200 is normal, but anything over 225 or so is considered a lot. Why? Well, I think it's harder throwing 5 times in a week and a half for 1-2 innings each than it is pitching twice in that span for 100 pitches. Warming up 6-7 times is also harder than warming up twice and throwing lightly between starts.