No it's not too simple minded. That's what I get from my D800e too. The number shown is an absolute worse case. I found that I get 50-70% more images than shown on the indicator for loss less compressed RAW. This seems to be the case with all Nikon DSLRs.
Gary in SE Michigan, USA. Nikonians membership - My most important photographic investment, after the camera. D4, D810, D300 (720nm IR conversion), D90, F6, FM3a (black), FM2n (chrome) YashicaMat 124, Graflex Speed Graphic 4x5 My Nikonians Gallery & Our Chapter Gallery