All babies are individuals. There is no one sleep training method that will work for all of them. I made the mistake in thinking that it would, that the "experts" knew all babies. A couple of people who have posted on here (@Tee20x and someone else, forgotten who sorry) had exactly the same experience as me by the sound of it.
DS was about 11 months when I tried controlled crying. He got more and more hysterical, not less, every time I went into him while increasing the time gaps. I did it exactly like you're supposed to. Exactly. I was calm and determined. All it resulted in was a clammy vomiting, terrified, shaking mess - him not me lol. I am a stubborn cow and carried on for 2 hours with him getting worse and worse till I copped on and realised that actually, no, he didn't fit the stereotype of what is supposed to happen and I hadn't been doing it wrong. It just wasn't right for HIM and for him it was bordering on child abuse. It took me a further hour to calm him down enough for him to go to sleep - by this time it was hours after his usual sleep time (the irony...)
I researched other things and did gradual retreat. It worked a charm, but I grant you it did take about a week and and a half, and a lot of extra effort. Was so worth it.
With DS2 he was a different personality. After colic finished (and that was hell!), it seemed that he was a baby that loved his cot and his sleep. He would get sleepy in my arms, I'd put him down in his cot and he would do a little sleepy smile and just relax straight away and off he went to sleep. Not a problem.
He's 15 now and still loves his bed, goes straight to sleep the minute he gets in usually. My eldest tends to lie there pondering life (so probably no different to what he tended to do as a baby, only when they're babies and they're the "lying there pondering" types none of their thoughts make much sense yet so no wonder they feel all confused and upset.
They are ALL different. There is no mould that they should all fit.