I wing it, after some time drawing something with certain proportions becomes a habit.
Like you know that elbow belongs in the area of the waist, and the hand should end up in the crotch area, and 2 leg parts are the same length, and guys on average have longer torsos, and so you do everything from those simple measurements.
As for height, I just take a pick that this character is like half a head lower than another one, no one will measure it with a ruler
I know my weakness is that I usually make bigger heads and I try to overcome this one now (I guess it evolved from drawing kids with weird proportions a lot), but I guess my characters look shorter because of it 