I've sort of cut to the end- I read 2/3 of the thread.
Here's my tuppence.
It's been my experience that parents who decide to try 'controlled crying' are generally those who have reached the end of the road. They're exhausted. They're on their knees. Their baby is grumbly and fractious because they're not getting any quality sleep. Their parent/s are barely coping. They're beginning to resent this little being who is wrecking their lives, their sense of being.
The whole family is on their knees.
That's where 'managed sleep' (hey, a different term for the same thing! 😊) comes in. Often, when you get to the point where this feels like this is the only option remaining - it works.
It rescued us as a family. I guess that, as I'd been screamed at, day and night for 9-10 months, my capacity for capitulating at the first whimper was gone. We did it properly. 1 minute, 2 mins, 3 mins.
It took two or three nights.
We were saved. Our days, all of us, we're so much happier, more fun. We were stunned at how easy it was. Child awoke happy and rested, as did we.
I did it again for my second at 7 months, but he was more robust and readily understood 'the deal'. One night.
Those who tell you it'll affect them forever, in all ongoing relationships etc are talking bollocks. Mine are early 20s now. Not seeing 'attachment' issues...
IMO if you aren't 'ready' for it', you haven't yet been driven to the edge of your sanity, where it might be the only way out of the exhausted nightmare you're all stumbling through. Bar 'alternatives'
Many who strongly and judgmentally condemn that decision have never faced the reasons why you might make it.
Mumsnet is full of people who have no concept of walking a mile in someone else's shoes.