[claudiawerner]

>A year later, guess what? I couldn't remember jack-shit. Moreover, I couldn't solve problems, which is basically the reason I was learning math anyway. Any bystander could have predicted this outcome, but I was blinded by my own entitlement.

I'm a third year university student; I did all the exercises set last year to do well in the exam and over the course of the whole year. And now, only one year later, I can't remember how to do some of the most fundamental problems. I can remember the derivative and integral of trig functions, but the method of doing even moderately challenging exercises with them I don't remember well and I'd need to look it up. I don't know what that signifies, but I have the impression that even just doing the exercises doesn't last long unless you use what you have learned semi-regularly at the least.

[ThirdFoundation]

To add to your point, I think this reinforces the value of spaced repetition learning. It's been show to been one of the best ways to actually retain information. So, as you said, just doing the exercises only gets one so far. You'll need to either use what you learned or at least do refresher exercises to better put what you learned into memory. The benefit is that you may be able to do these refreshers and greater intervals over time, effectively retaining the information longer.

For me personally, there does seem to be a tipping point where what I learned really sticks in my brain and degrades much slower. However, I can't seem to pinpoint where that point happens or if it is even consistent. There are some coding concepts I never forget, and some that seem to leave me within a month.

https://en.wikipedia.org/wiki/Spaced_repetition

https://eric.ed.gov/?id=ED427772

https://www.theguardian.com/education/2016/jan/23/spaced-rep...