I take my horn in about once a year just for a checkup. Then I take it in other times for specific probelms. I think unless your think your work is better then your repairman having him check things is worth it. I took in a clarinet I just bought that I thought all the pads looked pretty good on the top end, I mainly just wanted him to replace the bottom ones which I thought look ready to replace. He found 4 on the top that needed replacement too. He did the work for a reasonable price and I initially though it was too much work, but when I played it after he did, I was like wow, what a difference. My point is, a yearly checkup might turn up things you didn't even notice. of course make sure your repairman is not a used car salesmen and finds things that don't exisit. But finding a good repairman is another thread....