I think the key to succeeding in math classes was to do enough problems to see the patterns. Then, when confronted with a new problem, you can say, “I’ve solved a problem like that.” And while the path might be different, it isn’t that different.
There’s an element of that in music-making, too. Successful performance boils down to, “I’ve sung a piece like that before – so I know how to interpret it.” Successful sight reading boils down to, “I’ve sung a phrase like that before,” and successful group leadership boils down to, “I’ve lead a group with similar characteristics before.”
Do something enough times and pay attention to the patterns and your success rate grows quickly.