So this was supposed to be a colored sketch, but the reasons the lines look so clean is because I tried something new. Essentially I took that really rough sketch at the start (for pose approval), and then just started drawing over top similar to how I would ink drawings. I thought I had the ability to predict where all the lines would go even without a detailed sketch to work from, and it turns out... I was right! And it took a similar amount of time as a detailed sketch would have taken me. :3
I'm not sure I'll be able to do this all the time, but it makes me feel hopeful that I found another way to be even quicker at art than I already am. :p
Additionally, that thicker black outline was added with a layer style in Photoshop, and not done by hand.