Here it is:
What if books are used as buildmats to build a library. You only ever need ONE of each book, they dont get used up, they dont need to be hauled around, stockpiled and so on. Books like:
"Write 'The Metallurgy of adv. Metals III' (Smithing)"
"Write 'Cheese - An Anthology' (Farming)"
"Write 'The Brain - Do we really need it?' (Mind&Body)"
"Write 'Stick them with the pointy end' (Warfare)"
"Write 'What is FUN - A Contemporary Classic' (Philosophy)"
Each of the 5 library sections need 10 books that fit, so the 10 books that have (Warfare) are needed for the Library of Warfare. This means the library workshop itself takes a lot longer to build.
Now comes the catch:
Training is free.
Training gives instant skills. Do the reaction, instantly get the skill level you want.
Warfare trains any of the related skills to lvl4
Philosophy trains any of the related skills to lvl4
Crafting trains any of the related skills to lvl6
Smithing trains any of the related skills to lvl6
Farming trains any of the related skills to lvl6
Mind & Body trains any of the related skills to lvl8
So you write 10 books, outfit a library, and from that point on any dwarf can come by, read a book (the time this takes I can control, be it 1 day or 10 ingame days) and after that he has learned the collective knowledge of your dwarves on that matter. But you can only get to the levels I posted above. Super fast, but limited in range. This means your useless migrants get useful, but your already good crafters dont get maxed out, because a master-smith cant learn from reading a book.
There could still be rare masterpiece books that train to lvl10, or I make them even rarer and train to lvl 15.
I personally think that this would be a vast improvement over the current system, because its a lot easier to use, makes more sense from a logical point of view, gets rid of notebooks, and dwarves can only learn so far from theoretical knowledge before they have to continue learning a skill the old fashioned way.
The normal, xp/reaction related skill training I can keep, like the Tavern or the Apothecary. I could even add some simple ones here and there, like combat drills in the Garrison.