If I was in Stock or CSP I'd have gone through twice as many. In STS2 I've only discarded two sets of tires so far in two years.
All the rest have either been used for testing-practice or different conditions. Some are waiting for their day. I'll be pitching a couple sets of Azenis so I can mount Bridgestones on the wheels. Since Bridgestone supply is spotty, I stocked up before Nationals. Most of the used Azenis are far-far past any competitive life, and have no tread left. The new RT-215s were a just-in-case purchase.