I forget a lot of 3. But 1 and 2 didn’t really do mission rankings along those lines and were generally built around having to push through multiple rooms and hallways. Whereas 4(a) heavily emphasized wide open spaces and rushing to get those objectives.

6 was a MUCH better balance where the S rank actually often required a certain number of kills and many missions had ways to justify the ammo expenditure so that it wasn’t just “get a karasawa and then human plus”.