A girlfriend of mine posted on FB today about failed sleep training with her 5mo old. I shudder a bit because frequently "sleep training" is synonymous with Cry-It-Out (CIO).
I don't really believe in sleep training. Everything with babies and children is a phase. As soon as you find something that works, they grow, teethe, get sick and a whole other host of bullshit that f*cks it all up LOL
I think that it has more to do with your child's personality. I'm not a proponent of CIO. My first daughter slept like absolute shit. My son is an awesome sleeper (relatively, at the least!).
I think you have to just follow your babies cues and do what's right for you. For me, listening to my baby cry feels wrong and literally makes me sick to my stomach. I'm not going to ignore that because of some book. What are mothering instincts for?? If you don't feel that way, then fine! But don't let others pressure you into it.
The only thing I do differently this time around is pay closer attention to his "I'm sleepy" cues and not RUSH in as soon as I hear the baby cry, which I did do with my daughter (and I still think that she would just work herself up anyway, so it wouldn't have made a difference), but he often cries out or fusses for a minute and falls right back to sleep if I don't disturb him, further rousing him.