This is very wrong, and also a very common misconception.

The five year limit ONLY counts active duty which is totally voluntary and discretionary, and is also not in support of major contingency operations. It also does not count guard/reserve routine training.

USERRA was enacted to protect guard/reserve but also applies to regular active duty.

These types of active duty are exempt from the five year limit, and this list is not exhaustive...

1. AD for initial training. This can be years, if the skillset requires that (typical for pilots).
2. Any initial AD obligation incurred. Initial AD obligation is typically at least 3-4 years.
3. AD performing any additional training.
4. Any AD obligation incurred for said training.
5. Any service in, or in support of, major contingency operations. Until recently many guard and most reserve AD orders fell under this.
5. Any routine guard/reserve training (not limited to one weekend/two weeks, just has to be mandated by your unit).

So you can join the guard/reserves, do several years of AD for initial training, then monthly/annual training to 20 years, and retire without touching one day of your five-year limit.

It's also possible to do 20 years on regular AD... the first ten+ is typically all obligated anyway if you're a pilot, and you get five years of voluntary service. That gets you to 15. Somewhere in there if you do a lengthy school with a service obligation, then that would get you another five obligated. A two-year masters program with a three year payback obligation would do it.

Don't worry about the five years limit unless you want to do 20 years AD, or are in the reserves and want to do a lot of volunteer orders. New members can disregard any five-year limit issues, it doesn't apply at that point