I'm a bit confused by your question so I'll just blanket statement the system as best as I can.There are a lot of book sets that unlock unique perks that are designed to augment each play style or weapon archtype. Collecting all 7 unlocks a completion bonus perk that is pretty kickass or borderline OP.
There are schematics for all the things that the skill perks unlock (Not the books). For example, the first rank of of boomstick allows you to craft a double barrel shotgun, but you can also find a double barrel shotgun schematic, which teaches you permanently how to craft a double barrel shotgun. However, that schematic does NOT grant you any of the abilities the first rank of shotgun messiah, such as do more damage.
So the first rank of boomstick does this:
Maybe your aim isn't so good or you just like doing a lot of damage up close and personal. Either way a hobo with a shotgun is not to be messed with. Craft faulty quality Shotguns, deal 10% more damage, 10% faster fire rate, and 10% faster reload. Increases chance to dismember by 5%.
The schematic does this: Craft faulty quality Shotguns.
So a schematic will let you do the basic crafting is all, the perk gives you the full nine yards. Its more useful for forge, or bandages if you don't want to be a doctor but want to craft bandages, then find the schematic. If you interested in all the benefits, buy the perk. The schematics let you focus on your build and give you entry level access to some stuff outside of your specialty.