Extinction method at 11 months, she had gone from waking once/twice in the night after being rocked to sleep, to waking every 20-45 minutes and crying for me to put her back to sleep, if anyone else settled her she would cry and scream, but as soon as I walked in she would calm and go back to sleep then wake up minutes later only to start the cycle again, after a week of that I was so sleep deprived I just decided to do it one night.
I though ferber would be confusing, so just went downstairs and watched her on the monitor. She cried for 15 minutes the first night, then went to sleep and slept through the night for the first time!, same for the next 3 nights then the fifth night was 35 minutes before going to sleep.. I looked it up and it's common as a last ditch effort to get you to relent.
The night after she went straight to sleep no fuss or tears, and she's been the same every night since in fairness, she goes to bed happy, we say goodnight and she looks at her books before falling asleep. If she woke up in the night we'd see to her, get her a drink etc, and we still do if she ever wakes but it is very rare, and when she does she goes straight back to sleep, it seemed to reset her whole sleep requirement.
Before we did it I thought the process sounded barbaric, but I couldn't believe how well it worked, and how much better off she was for it, she went from crying for at least an hour a night (every time she woke, multiple times a night and resisted going back to sleep etc) to not crying at all, nothing.
I think age is massively important thought, at 11months I just knew it was going to work for her for some reason.