I noticed that when I do a technique study of Line work in my anatomy exercises my line work is much stronger versus when Im doing photo reference. Obviously because the artists I am looking at have already done all the work of creating a form in line. My question is does it really hurt me to do my anatomy studies from predrawn references or must I sort it all out from photo reference.

Honestly, my taste far exceeds my talent and its hard not to become incredibly frustrated when Im drawing, so much so that it is hurting me more than helping. I cant tell you how many times I've torn out pages out of my sketch book over the years and just walked away from drawing for a lengthy time only to come back worse than when I left off. I wouldn't mind being off in my studies if my line work didn't look so subpar on paper. Digitally I can get the handicap of photoshop of coral painter to give me nice line work, but on paper my lines have no energy regardless of speed and avoiding using my wrist. The only time my linework seems half decent (which helps build atleast enough confidence to move forward) is when Im copying someone else's line work from reference so I'm wondering how much is this really hurting me when I'm doing my skull practice...