I wasn't a believer in practice drawing, until I took a class from Jamie Wallen. And after that I was a firm believer. He doesn't recommend drawing on a white board or other erasable surface, because he says you need to save your drawings to see how you are progressing. Start by drawing your motifs small, even though you may eventually want to make them larger. My theory is that you aren't really training muscle memory - you are training your brain so that the twists and turns in the design will become natural to you.