I have a 9 month old and I actually did not go in with mantra cries. I think it really depends on your LO. Mine often would do his mantra cry for a while and then calm on his own. If I had gone in I would have been underestimating his abilites/skills, as he was often able to calm on his own. During the daytime if my LO was showing some SA (i.e. if I was in the other room), I would again wait for a few moments. He would sometimes whine for a short period and then get distracted by something he was playing with. If the whining turned into real crying I would go in, get down to his level, and hug/play with him briefly. I didn't pick him up unless he needed that to calm. Then when he was calm and engaged I would go back in the other room and finish what I was doing. I believe in Tracey's book she talks about just giving them as much support as they need, and I think that really helps them to develop their self-soothing skills!