Hi op. In sorry you're ending up more confused. I think you've just walked unwittingly into a topic that tends to get quite heated no matter what the original question was.
For us and our dd it worked really well. I can't remember if I read it whilst pregnant or when dd was very young but at about 6 weeks she seemed to be falling into a routine so I used sos to guide times etc. I also felt like I had no idea going in having not had much experience with babies and a lot of what was in the book seemed to make sense. But I should add that my dd never had much trouble getting to sleep. So long as she was fed and swaddled she just drifted off in her bassinet. So I think if you have an unsettled bub, or colic or reflux or anything like that it would probably be a different story. I'm currently pregnant and will aim to guide bub into routines around the 6-8 week mark if it feels right, but who knows what this bub will be like! Good luck. I hope this doesn't put you off posting for advice.