If we’d followed though back in the 70’s English measurements would be nothing but a quaint memory today.
English metrics (ha! ironic, huh) were derived from common relatable instances (pounds, stones, gallons, feet, yards).
True metrics (ala ‘system’) were designed by lazy scientists and aficionados that thought it would be neat to only have to worry about things in tens, hundreds, etc. Screw them...I never bought a deciliter of anything - never will.
So today a football field would be 91.4 Meters and the base paths would be 2743.2 Centimeters? ;~))
I spent forty years working for a manufacturer of hydraulic pumps and control valves. I was in product design and development. Over time it became apparent that it didn't make a bit of difference which system we used. Our measuring equipment could reliably read to 50 millionths of an inch, push a button and the reading switched to millimeters. The CNC machines were programed in P code and the industrial engineers could handle either system when programing the cutter path. Stand alone machines allowed a machinist to to mechanically shift back and forth as easily as you could shift gears in a stick shift auto. I was the manager of our CAD/CAM system for some fifteen years and we routinely made 3D solid models of our parts and then rendered them as 2D machining drawings with English dimensions for our shop and metric for our foreign subsidiaries.
Metric has made great noise about it's simplicity because all measures are related by powers of ten. BFD! Angles are measured in degrees (360/revolution), minutes (60/degree) and seconds (60/minute) in both systems because not everything in nature works smoothly when measured by decades. Same goes for time intervals (& second, third, and fourth derivatives). As for angular measure in Radians or Grads, don't even bring them up.
Physicists may measure Angstroms per Picosecond and they are just as guilty of using bastardized units as those of us in the inch/pound/second camp. American industry was busily making "modular metric" products and no one noticed because it doesn't make any difference. The American consumer doesn't care how things are measured, his only concerns are how much does it cost, how long will it last, can I take it to a dealer and get parts.
There are some serious disadvantages to the Metric system, one being the measurement of pressure (force per unit area). One measure is Pascalls where one Pascall is 1.450377×10−4 psi which is ridiculously small, the other is the Bar which is 14.50377 psi, a rather large unit but still slightly smaller than a standard atmosphere.
Regards,
GtG