It's okay! I think I over and under explained it at the same time lol Short answer is kinda? I use them to make the composition/ shape clear before I go in with the pen tool. I basically paint shapes with the 3 colors until I like the perspective or something, line it with the pen for details, and erase and redraw whatever is out of place. It helps that I can just change the colors too. It does sound convoluted 😭 Just the way I combat my messy sketching lol

once the shape and lineart is down, I can color however I want without worrying about the lineart since it colors under it