The grade fades by summer. The skill you built getting it stays in your hands.

Marks are a compressed summary of one moment, useful for a year or two and then almost never asked about again. What outlasts them is whatever you can actually do, which got built during the work rather than recorded at the end of it. Two people with identical grades can walk out with very different abilities.

When you are tempted to optimize purely for the score, ask what you will still be able to do in two years. Learn the part that transfers and let a few points go. The exception is a grade that opens a specific door you want, which is worth chasing knowingly.