Knowing you’ve reached the limit of your current capability is boring because you know the next few practice rounds will be much of the same, with minor improvements that provide a dopamine rush.
Regardless, nothing has changed in the age-old saying of how to get to Carnegie Hall: Practice, Practice, Practice. The practice is the boredom, but without training your muscles and building up myelin sheaths, you’ll never be good enough to automate most of the music to an extent that you can improvise on top of it (the fun part).
I guess my point is akin to OP’s, in that boredom isn’t inherently a bad thing, but a means to an end. Without the boring practice, we wouldn’t have experts/artists...and even then, the practice doesn’t have to solely be boring.