Ask HN: Any clear indicator of learning progress in complex fields (CS, Math)

I tend to spin my wheels in lots of my activities. I think it probably hinders my progress in these areas. I ask this question because I've been trying to gain weight recently, and I had the epiphany that if I weigh myself regularly, I can quickly see what the trend is and correct it by taking proper action. I know it may sound obvious to some of you, but I guess I'm a slow learner :)

The point is, do you know any clear indicators, particularly in computer science and mathematics, that would allow me to apply the same method?

I've been successfuly learning german with duolingo recently, and I noticed it's packed full of indicators that allow you to apply this `take action -> get feedback -> apply correction` cycle.

(Maybe the domains i gave you are too broad and I should restrict it to specific sub-skill?)

Thank you!