Of course it worked for you Addison - as you say, your son fell naturally into the sleeping routines.....and it's highly likely he would have done so anyway. The problem is with forcing a child into this routine and leaving them to cry for such long periods.
I'd be more inclined to believe your little fella was going to be an awesome sleeper from the start (as lots of them are), after 3 kids with 3 different sleeping patterns I can't believe a book can take all the credit!