The real issue is separating "needs servicing" from "manuf suggested servicing". Needs means the reg is not performing correctly, not that some arbitrary time interval has elapsed. "Manuf suggested servicing" is simply there to keep the warranty in effect and as a revenue source for dive shops. There is no magic in a reg with a 2 yr service interval, just marketing. Pretty much all of us self service types have pushed the time limits way past the 1 year mark and most I know go over the 2 yr mark. Regs rarely catastrophically fail, in reality they start with subtle signs of problems that slowly build over time. If you are doing proper self checks on the regs you will see the problem way before it becomes so bad it effects a dive.
The idea that annual service somehow keeps problems from happening as opposed to longer service intervals is simply a myth. There are no parts in any reg that wear out or significantly degrade is a few years of average use. Granted, if you mistreat your reg, odds are it will take the abuse long enough to make it to the next service interval, that are actually pretty tough machines but if you take proper care of your reg, it will go a lot longer that a year or 2 without service. Then there is the service introduced failure. Any time a machine is dissembled there is the chance of something not being done correctly introducing problems or worse causing damage. There is a very good reason for the "if it ain't broke, don't fix it" rule. Over the years, one of the most common service suggestions made on this board is to never have a reg freshly serviced and leave for a trip. Experience has proven that the odds are greatest for a failure soon after service, not after a reasonable interval of proper service.