I could be wrong, but I think I remember reading somewhere that once you serve 20 years outside of the academy the 4 you spent at the academy start counting toward your pay and retirement.
After 20, the four years DO count, not an urban myth - current mid
kp, that is correct. Your SA and service time an be bought be back toward a retirement... Source... My neighbor and best friend did this. I have a copy of the document that references it as I had several GS offers I considered.
And the 4 years at a SA do not get tacked on 'at the end' to make a 20 year retirement now 24... I asked several of my close friends who retired in the last 6 months. None of them had that time added on.