i feel lucky as i was born at a time where the old imperial system was phased out for the metric system. So i never ever learnt the "old" ways.
I find that my degree of accuracy with the mm system to be much more favourable when working on scale models.
1" = 25.4mm
so to get a 13" rotor multiply it by 25.4 then divide by 24 to get the scale for the cars to the nearest 0.1 of a mm! much more accurate than those 37/3 and a 1/5 etc.
plus the japanese use it so again it works out more acurate if you use the same method of measuring as them then you dont get a tolerence creep.
i myself got my first drawing board (a rotoring A4 slide rule) at age 6. and a rotoring A3 age 9. then autocad since 1997 so and have only realy stopped drafting in the past year as a proffession. So i have a good understanding of how to design.
And the metric system is so easy to use.