I used to shoot 2 cases a year when I was shooting CAS full time. That was out of the 4 guns you use in CAS. Plus, competing every weekend.
Now it's more like 6-7 lbs a year. Mostly all practice, because i'm not one to always be working on different loads. I find what load the gun likes, and just stay with it.
4 cases a year is a lot of shooting.