This reminded me… that company is selling a combined cylinder+regulator and they overhaul the whole lot every 5 years.
If the 1st stage reg fails, you are done, no matter how much gas is in the cylinder.
But maybe they rarely fail, except (like so many things in aviation) just after being serviced
I service my scuba regs every 2 years or so but that’s because of water exposure. For aviation usage I think they are good for 10 years at least.
What needs to be done in these? I know there are external o-rings, but is there something inside which is easily serviced?