The issue with using books to train, is that if you transfer it to skills that involved combat, such as windmill, players can go directly for the books without even needing to use the skill. I believe cooking did this right in live mabi, in that you needed books but you required training to go along with it. Then you hit the issue of balancing, and the annoyance of having to hunt down the books, especially in the cases of secret shops.
It'd help the life skills, to improve what's produced from them now, such as blacksmithing gets a more serious boost from its equipment, preferably lower stat equipment gets a more serious boost to make it keep up with higher stat equipment, so that players don't feel like they should use one specific weapon their whole game life. Some skills like weaving... i really don't know what to do with that.
But combat skills... i'll probably complain about most, cuz they're honestly
not that bad. It's a one time tradeoff, a bit of effort in combat which is what you're going to spend most your game time doing when you're not standing around talking. So learn how to effectively use the skill, and the training isn't a problem most the time, and even when it is it's a one time tradeoff. Train it, then it's done, you never have issues with it again. It's not like PTJs where if you don't do so many within a certain duration, it loses counts and thus rewards. The benefits are permanent unless you do a reset.
_________________________
Discord: Tonkatunk#7079
https://github.com/Tonkatunk/Mabi-Pro-Lazyfae-Mods