Challenging yourself to draw the same poses with different lengths of time would be hugely beneficial.

I’d recommend 10 sec, 30 sec, & 1 min. The short time frame is valuable because it forces you to make decisions and trust your gut, which will create more confident lines, and a myriad of other skills. You’re doing a great job, mind you; it’s a good practice for all artists who want to do study the human form.