Be aware that the five year limit is often grossly misunderstood... there are a wide variety of orders which do not count against that total anyway. During OIF/OEF/ONE it was almost impossible to exceed five years with non-exempt federal orders. You'd have to do something like war college professor for five years.

In fact it was mathematically possible to leave an airline, go on regular active duty as a pilot (or other MOS with a lengthy training obligation), do a full 20-year AD career, retire, and then return to the airline with 20 years accrued seniority.

Make sure you understand the exclusions before you worry too much about the five year limit. Probably would me more of an issue if you wanted to do a lot of state guard orders.