Arvock
If you get a +7 compound, there had to be an alchemy book involved. Even superior only give +5 without one, Junior and Primary give +4. That's set in stone without alchemy books.

NoMoreFcuk
The reason why alchemy books are worth having is when you're making higher level equipment. They can actually save you a lot of money. And some compounds a book is needed for, some compounds just use it to increase the chances of success.