Checking a manual never hurt - but consider this:
A team player is probably going to throw 1-2 cases per week, on average. Split the difference. That's ~40 cases per 6 months.
This doesn't include competitive play paint, etc.
Now - if you had to send your Axe back to Empire every 6 months - I am not sure about the rest of you..but I'd throw a fit based on shipping expenses alone...even 1x per year seems a bit often to be without a marker.
They probably allow you to push their regulator to failure and repair on an as-needed basis..or the manual could/would offer advice/insight as to who and how often to get the reg serviced.
I'm siding with Martix - never...unless it fails.. but it also never hurts to RTFM.