I think a lot of it has to do with confidence with pencil strokes and the capability to move on.. I spend a lot of time loosely sketching, erasing, redrawing, erasing, redrawing.. I also noticed certain things I hate to draw, namely foreshortened limbs (the hand and arm coming up front), bars of a bird cage (I think in part because I had no reference to a bird cage), and female clothing. I think I grew too comfortable with comic book women who just wear lycra.
How does one speed up their drawing? Is it by just drawing religiously, or forcing to move faster?