My wife and I own one regulator each, both Atomic, with a suggested two-year service interval. There's no "free parts" program to worry about, and the warranties aren't contingent on service. So for us, service isn't much of a hassle or an expense.
I waited two and a half years to have mine serviced the first time so it would be closer to when I would be using it rather than just hanging out in the reg bag. I bought my wife's reg last year for her birthday. So this means once a year, sometime in the spring, I'll be taking one or the other reg in for service.
This is probably more often than is actually needed but it's an easy way to keep track of service intervals.
Now if I had a bunch of regs, I'd probably be more inclined to do the service myself on an as needed basis.