The other guys said some really helpful stuff, I can only tell you to not forget that a lyne of action practice is not about perfection, what you do here is look for a way to describe a shape due to understand it, or a line that YOU THINk describes something in the best way.
(Really you can practice for whatever goal you have, but I try to have that in mind to avoid being stuck in an cicle of unfound perfection. I think that can help)
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