The World Does Not Reward Effort
Say you have to pass a knowledge test. Nowhere on the test it measures how much effort you took to get that grade. It doesn't matter.
The only thing that matters, for the purposes of the test, is how well can you get the correct answer.
High-effort might be positively correlated with higher grades, but in no way it is a requirement.
One would like to design a test -- or a world, for that matter -- where effort and merit was the measure of reward... but this is not the case.
The only measure of reward is how big of a problem can one solve -- or how much value can one bring -- for someone else who is willing to part with their money.
For example, if you go to a restaurant, you pay for the burger because you value the burger more than the amount of money it cost. You have no idea (and frankly do not care) about what's going on on the kitchen, as long as you get a satisfactory burger at your table.
Same thing applies for almost every reward. The party who's going to bestow the reward frankly doesn't care how much effort you took, just how much value you added to them.
Now, for rare and high-value things, it tends to take on more effort. After all, were it easy and low-effort, it would be readily available, thus low-value. But again, effort is not the goal.
Effort is a tool, not an end in itself. Effectiveness and goal-directness are way more important.
To get rewarded, all you have to do is to solve a problem for -- or bring value to -- someone else.
If you put just the appropriate and satisfactory amount of effort, you can free up the remainder of your resources (time, energy, mental space) for other activities of your choice.