I've got one that I got from them in 1995 that gets shot a lot that is still going strong. Its a 10'5" upper on an SBR lower. Its accurate and I have zero issues with it.
How often? I usually go to the range at least once a week, but that is not required as I have my own range at the house. Cant say for sure, but its got more on it than most guns ever see.