What do you think of larger time skips in stories with a level-up system? Do you prefer experiencing the entire character progression up close, or do you value a fast-developing story more? I’ll leave out the classic ‘character accidentally defeats a super strong opponent and gains enough experience points to become overpowered’ trope here.
You shouldn't be skipping fights or challenges that grant level ups
most of the time. The only acceptable time to skip fights or challenges would be if you do da ting, show the character learning and refining how to win, and then skip past them doing
the exact same thing over and over (grinding).
Frankly, I'd advise doing the 'beat a strong opponent' approach instead, if you didn't directly say it's not allowed. Fighting strong opponents is both better for engagement and faster than grinding, without requiring a time skip. But uh... You do you, I guess.
I would never, ever skip level ups themselves though, unless they don't matter... And they should matter or why have them at all? Theoretically, you could review the level ups after a time skip, and that
should be okay though.