Problably I am not 
Learning by doing, since designing my kitchen and living room last year.
So this purpose is all new to me, but might save a couple of hours every week!
Very interesting about placing lines at intervals!
Although I am not sure how you do it as explained?
I tried, but when moving a line over a surface with the move copy (crtl move) function it says “Invalid Length” when I type x20.
I can move it once at 0,6 meters by just typing “0,6”, but when do I type “x20”