I practice comparative drawing, I barely measure anymore, and what helps me the most to get more accurate drawings is working the drawing side to side.
It’s a simple concept, I always start with the top of the body and work my way down but I don’t let one side of the drawing get too far along before I switch to the other side. The reasoning behind this is that it is very hard to compare a line when nothing is next to it. If I drew the right side contour of a person from top to bottom there is a much higher chance of its accuracy being wrong as there is nothing to check it against. Instead as I work down the body moving from left to right I compare what I’m currently drawing with what I drew before it.
Also moving side to side gives me a chance to feel the volume of the body and how it fills the space. When I draw the shadow shapes and contour of a pectoral I try to feel how it rounds around the rib cage like a barrel.
With this method I almost never have an issue with the width of the figure, length is another story.
