As a musician, one of the things we learn early on is that practice does not make pefect; rather, perfect practice makes perfect. If you play the same phrase over and over, with the same mistakes, you're teaching yourself to make those errors every time. The more ingrained they get, the harder it becomes to correct them. I think this holds true for how we practice and see things in art too. This is one of the reasons why it's harder to see issues in our own work than in the work of others. Mistakes that we make again and again become invisible to us. When we play back a recording of ourselves playing a piece, or look at our art in the mirror, we get a new perspective on what we've done. Mistakes jump out like a sore thumb.
When I was practicing circles and ellipses, I was concerned that I'd develop faulty muscle memory if I drew a lot of them that weren't exactly symmetrical. I was afraid that I'd stop seeing the symmetry if I got it wrong. (See my previous post, "Lines, Ellipses, Perspective, Cross Contours," if you haven't already.) Apparently, this concerned somebody else too. I searched around the internet and
