There's an awful lot of bollocks talked about fixed-wheel riding. In this it is much the same as all areas of cycling.
I've always stuck with traditional, lowish gearing, 67" or 63" (more the latter as I get older). Certainly I could get up just about anything on 67" in my younger days. I can still comfortably hold evens on the flat with either gear.
It's always a pleasure to climb on to the fixed after riding gears for a while. Conversely, it's always a pleasure to ride gears after a period on fixed.