Run multiple queues: it's always easier to see what's wrong with your drawing on each particular stage after you've taken a short break; but there's no reason you can't work on 2-3 of them at once, step-by-step, allowing to break a, say 2 hour work session into 3 sections of 40 minutes - as opposed to non-stop crunching all those 2 hours into a single drawing, only to end up battling against hurdles you would've easily vaulted over with a fresh mind.
Use split-sketches: by breaking an idea down into composition/proportions, structure (anatomy, perspective), linework, lighting/shading, with a separate preparatory sketch for each, you can eventually establish a very efficient workflow for the finished drawing, ridding of moments of indecision and mental overload where you have to figure out the perfect harmony between all those elements on a single canvas.
Bonus advantage: it's also helpful for figuring out which of those aspects in particular you want to be the main focus of your drawing - maybe the dynamic linework; maybe a moody wash of lighting; or just keep both muted and focus on bringing clarity to a complex scene through crisp structure and composition.