Ahhh, sorry for the late reply!
As for proper developing speed, I’m not too good at it myself. However, from what I’ve seen, I recommend choosing an ability that is tricky to use to an extent but refrain from having really specific conditions (unless you’re going for a natural fighter mc that doesn’t rely on the power).
Ensure the skill isn’t something that can rapidly grow in any situation, and only make it possible through sheer effort of breakthroughs ig?
Its main ability shouldn’t be anything correlated with growth unless it’s quite restricted. Pretty important to be mindful of “plot armor” as that could be a big wrench in story likability.
Plot armor is probably the thing you should be mindful of the most and you should be fine i reckon ( ͡° ͜ʖ ͡°)
(I typed this in 3 different times I was able to come online, my apologies)
