It took me almost one hour to put my older one to sleep with rocking, singing, walking when she was a baby and now she is 7 years old still sleeps with me. She has the habbit of playing with my hair before she falls asleep and it is so itchy and annoying. In the morning if I wake up and she usually will too even it is still too early for her.
With my younger one, after milk, read books, put her in crib she falls asleep on her own and even if she wakes up during the night she falls back to sleep on her own. I am so happy that I don't have to co-sleep with two.
I don't know and care if there is any long-term benifit to sleep training but I really enjoy the immediate benifit of sleep training.
