Retropear, I attribute it to luck. Some babies thrive on a fairly rigid routine, others don't.
I think you'll find I haven't ripped Gina or mums who have found her books to be extremely helpful to shreds. If you'd like to point me to where I did that, I'd be very interested.
But do you not see that by proclaiming that luck has nothing to do with it and that GF routines will work for every baby you come across as pushing an "I know best" agenda yourself? There loads of parents who have found GF very helpful, but there are also plenty of parents who've tried GF and not had success. I think that was just down to luck and the individual babies. You, on the other hand, don't think that luck comes into it at all so, again, why do you think those parents failed? If it's not a problem with the method, and there is no element of luck involved, then it suggests you think it's the parents' fault?
GF was never going to work for us because DC1 was quite ill as a newborn, often vomited up entire feeds so needed to be fed all over again (GREAT for my weight loss, not so much for any semblance of routine), found it hard to sleep other than in short bursts, and once he started to recover needed feeding up because he'd put on no weight at all between two weeks and eight weeks. There's luck for you, if you want a rather extreme version of "it's mostly down to luck". And DC3 is deaf, and there's a reasonable body of research suggesting that expecting deaf babies to go to sleep by themselves in a dark room can actually cause long-lasting sleep issues and problems around bedtime. So I'm not emotionally invested in this one way or the other. I do remember dusting off her book with DC2 and DC3 and wonder how it was supposed to fit in with doing a school run for older children, though.