If and only if the resulting expected value is greater than the opportunity cost. If the alternative is effectively wasting your extra free time, then sure. If not, then it depends (on the value of the change in grades, the value of the change in learning, and the value of your alternatives). Regardless, the answer isn’t binary: in general there are diminishing returns in grades and in non-grade-goals; you should neither optimize for grades exclusively nor ignore them.
If and only if the resulting expected value is greater than the opportunity cost. If the alternative is effectively wasting your extra free time, then sure. If not, then it depends (on the value of the change in grades, the value of the change in learning, and the value of your alternatives). Regardless, the answer isn’t binary: in general there are diminishing returns in grades and in non-grade-goals; you should neither optimize for grades exclusively nor ignore them.