I have three triangular engineering scales on my desk. I plot drawings out to scale.
My "ENGINEER" scale is in inches, and does the scales 1:1, 1:2, 1:3, 1:4, 1:5 and 1:6. I use those scales on inch drawings whenever possible.
My "ARCHITECT" scale is in 1"=1', 1/2"=1', etc. I have done drawings to these scales, but not frequently.
My "METRIC" scale does 1:100, 1:125, 1:75, 1:20, 1:25 and 1:50. I use these scales on my metric drawings. I would really appreciate a metric scale equivalent to my inch ENGINEER scale described above. Then I could prepare scale drawings in whatever units I damn well please, and scale the drawing with whatever scale I damn well please.
At home I have another metric scale that does 1:1, 1:2, 1:5, 1:10, 1:20, 1:50. This will be useful if I ever forget how to multiply by ten.
The nature of what I do allows me to make drawings 1:1 scale most of the time, and I strongly prefer this scale. If the scale is not 1:1, I start wondering how the end-user, possibly me, will take advantage of the drawing scale.
JHG