It worked for my 9mth old dd. she has now been sleeping from 8pm to 6:30/7am every night for the last 3 weeks. She doesn't even cry anymore when we put her down.
It is different for each baby. Some can take only a couple of days and others up to a week. The thing is not to back down, just keep the goal in mind.
This was our schedule for the first three nights:
night 1: you go into room after 1 min of crying, then after 3 minutes, and then every 5 minutes after that for the first night.
night 2: go into room after 3 minutes, then 5 minutes, then every 7 minutes after that.
night 3: go into room after 5 mins, then 7 minutes, then every 9 minutes after that.
As you can see there are increments of 3 minutes. We did not pat her or anything when we went into the room. Just put her back into a lying position and told her we loved her and walked out. The first night that we did this we first gave her a teddy bear and told her that from now she would be sleeping with her new friend etc, that we loved her and were not abandoning her.
Although she now sleeps during the night, the naps are much harder. For the naps during the day she can cry up to 30 mins before settling down. But i have been told by others that the naps during the day are much harder so I am not that worried.
Good luck!