Let me first begin by introducing the 80/20 rule (Pareto principle). Its a distribution related to work to effect or reward to time ratio, the idea being 80% of the initial work can be done with 20% of effort and the remaining 20% of work requires 80% of the remaining effort to get done.
Think of an example where it takes 100 mins to revise for and score 100 on a test. To score 80 takes approximately 20 mins of revision time. So perhaps, the first 80% are marks for relatively easy questions on topics. To improve by 20 marks and score 100 on that test requires 80 more mins of work. And can be seen as tackling the much harder questions on the same topic.
Its important to understand how important grading is. If the highest grade is below 80, then I could do 5 different tests and get the top grade for them. If the grade is above 80 then I have less time to spend doing better on other tests. And in the worst case scenario of needing to get 100% I can only confidently get the top grade in one test.
My philosophy on studying and life has stemmed from the idea of doing just enough. Because it gives me the maximum amount of time currency for all my other stuff.
With every task I do, I now always ask myself how well do I need to do this?
I don’t need to be the world strongest but I do want to be in the top 10% of my weight class; I want to be fluent enough in Japanese but i don’t need to learn to write; I want to travel but I don’t need to live luxuriously, nor do I feel the need to travel to a place just for tourism; I do want to be a very good mathematician and to counter the effects of 100% time dedication I’m just slowing down my journey, doing the achievements I want over a longer amount of time. etc etc.
TL;DR Time is a valuable currency, don’t spend more than you need on things you won’t use