I am assuming that we are just trying to establish rough ratios or perhaps measurement could be used to establish the orthographic views of some objects.

This is correct. The focus is not on accuracy, but rather precision - that means deciding what proportions you're going to aim for ahead of time, but not strictly requiring them to be entirely correct. There will likely be situations where you fudge things a bit - taking something that is 39/50ths along the length of a given dimension, and deciding to put it at 4/5ths for the sake of simplicity. As long as that is a decision you've made ahead of time, in your orthographic plan, then that's entirely fine.