Well, if you only care about vertical and horizontal spreads like iron condor and calendar. But everyone wants to know the exotics, things that no textbook covers. In another word, they're looking for the holy sizzling grill (sic, but you knew that was coming).
The exotics are just the multiple basic verticals stacked up together sometimes in equal ratio, sometimes more on one side than the other. So if you are able to understand the basic spreads, you can create your own "exotics". No textbooks can possibly cover all of the "exotics" that can be created.
I don't believe in relying on others to hand you the holy grail (not grill). I can create my own holy grail to earn me some good money for me to buy a real nice grill.
