I check my valve springs often and replace as needed. I'll check bearings, compression, and leak down about mid season just to see how things are. Other than that, for me anyway, I leave it alone. At the end of the season, I'll check lobe lift on the cam just to see if there's anything there. It won't come apart unless something lets go at the track or the numbers start dropping off. Last engine I ran went a full season with several test and tunes with only a valvespring change.........My buddy is still running that engine today.............and that was about 6 years ago........even still runs the numbers it did when I had it, which really surprises me...........but hey, it works!!!