Gotta say, I side here with FFF.
Once airbourne, nav should revert to mental dead reckoning since eyes need to be outside of the cockpit.
I keep it simple with measuring using thumb/span and then depending on aircraft apply one of the following.
Using multiples of 3 and 6 minutes is easy. Distance covered is obviously a 10th of TAS for 6 mins and half again for 3 mins.
Or use miles per minute and fly at a selected airspeed. (Even RAF fast jets do that to keep the maths simple!).
I am dead set against carrying lots of unnecessary items in aircraft as 2 major problems become obvious. If you become dependant on a piece of plastic, what happens if you drop it in the cockpit and can't get to it? Then you end up reverting to the basics, which you will not be very polished at. If your plastic aid then ends up in a place where it can cause a control restriction?
Rather not carry it in the first place. All you need is a map, compass and clock.
Obs cop