It worked for us and we didnt' really have relapses. If she got sick or teeth, we had awake nights, but I just sat by the cot patting. When I say controlled crying, I was there with her most the time, but I did try not to get her out of the cot. I would pat her to sleep with her lying in the cot. It worked well and meant she didn't get upset.
This was my experience with daytime sleeping, as night time was not so much of a problem early on. I tried a gentler version of the tweddle modified controlled comforting for 6 month and under (so you don't leave them for more than 30-60 seconds). Things got better within about 3 weeks, and while he still wasn't the best daytime sleeper, at least he was having regluar sleeps, and a bit happier about them.

It was very hard for me to do though, very emotionally draining.