How come you thought it was a waste of time? I've always seen it as key for keeping stuff sorted. For example, my study notes use colors for different subjects so I can find info fast. Even on my laptop, I color code folders to spot what I need right away. It saves me time and stops me from getting confused. Maybe it's about how you set it up, but I couldn't do without it lol.
Haha oh man I've been there lol. The trick is to pick a system before you start, like 3 colors max for different categories, not a whole rainbow. I use one color for main ideas, one for key details, and one for examples or my own thoughts. If you just grab a bunch of pens and go wild it turns into a confusing mess real quick. Keep it simple and consistent, otherwise you spend more time picking colors than actually learning the stuff.