There was once a ceramics teacher who did an experiment with his students. He told half the class to make as many pots as they could over the course of the semester, focusing on quantity not quality. He told the other half of the class to put all their energy and inspiration into making the single best pot they could. He told the first group they would be graded solely on quantity and the second group on quality.
At the end of the semester the teacher compared the pots of the two groups. Guess which group had produced the best pots?
Those students who had focused on producing as many pots as possible were free to practice without fixation on a finished product. They were able to learn and improve their skill. Ironically, the group that was told not to think about quality ended up producing finer pots. It appears that we learn better and faster when we are focused more on the practicing then on the outcome, a concept beautifully described in the book “The Practicing Mind.”
Simply put, sketchers learn faster.
Let yourself scribble, jot, sketch. Just fill up the page. Just keep your pencil moving and your eyes observing your subject. Just let your brain ask questions about what you see. If you do this regularly, you will learn much faster, you will improve. Ironically, you will begin to produce the superior images whose elusive promise inhibited your learning in the beginning.
This learning principle applies to most physical and intellectual pursuits that I can think of.
Try it out. Leonardo da Vinci did.