When I first started using the shh/pat, I was coming from 8 weeks of letting my LO fall asleep on me...or anyone else, for that matter. At first, it started that way because I didn't have enough energy to move around (had a c-section), and plus, I had no idea that it might be difficult to then get a baby used to sleeping in their bed. Yeah, Ms. Clueless right here!
Now, at 4 months, we can use shh/pat splendidly to get DS to go down for his naps and to sleep at night. We swaddle him, walk him around for about 5 minutes, sing/hum, stand by his crib and sing a little more, and then lay him down. We only have to shh/pat for about 2-3 minutes after his eyes shut (he's good about falling asleep the rest of the way by himself).
You just have to keep using it, because not only is your LO getting used to it as a cue for them to go to sleep, but you are getting better at recognizing and reacting to their sleepy cues. It just takes practice and getting used to your LO. I know, no quick solution, but it is a simple one
LOL, now, we're having problems extending our naps past 40-45 minutes, but that's our LO...he thinks he's ready to go for another 2 hours.
My LO still can't go to sleep all by himself, but there is absolutely NO APing going on, so we're not worried. It's a means--and a healthy one at that--to an end: independent sleep. We'll get there eventually
Best of luck to all of you fabulous mommies!