RE: How many years do you stay at each class and why
About one year at novice/sportsman. Going on ten years in and out of intermediate. Without life getting in the way, I probably would be at least advanced by now, maybe masters. There are several I know who started after me that are masters now.
I moved from sportsman after my first and only win, mostly because I felt the routine wasn't challenging enough. My last contest I almost stepped back down to sportsman because I had been out for a few years, but toughed it out. I finished last out of five, but it was a solid group and no normalized scores under 3600, so I considered it a success.