I actually saw a presentation video of this on the local school network.
I agree, it is good for people who've gotten out of control with screaming and possibly other 'bad habits.' (which I had, at least in my own opinion.)
I use it, but not exactly as presented. I don't force my kids to go to time-out. I use a consequence that makes sense, and that's it. (Like if the issue is playing around at the dinner table, "3" means I take your plate. If it's playing rough in the bathtub, "3" means an end to bathtime.)
And it does give me something to do besides start yelling.
For example, the whole dinner-bath-bed routine with three tired tiny kids was just insane.
Now, I almost NEVER even get to "2" with anything with my 5 year old. 2 1/2 year old, she is starting to really understand it too.
What it's done for me and my kids is---it gets their attention! Because I did this and stuck with it, every time we got to "three" whatever I said was going to happen happened, they know that when I start counting, I'm serious. It will even get their attention so that I can say something else to add some "teaching" to the moment.
Also, on the rare occasion I do use a time-out as the "punishment", it's for as long as they feel angry, or until they feel they can stop doing XYZ, it's about when THEY feel in control. Not about some arbitrary number of minutes. I've had my daughter come to me after 30 seconds to a minute, tell me she's going to stop, and do it.
I've had my son stay away longer than his prescribed 5 minutes because he was still mad. *THAT* to me is the purpose of any sort of "separation" is to teach the child that when you want to hurt someone or something, you should go away and cool down somehow rather than following that impulse.
So, in short, I think my modified approach has worked wonderfully with my kids. and while it is teaching "avoid the punishment" i suppose, to me it's also giving them a chance to change before you just swoop in and take action. And it's worked with my son to give him an absolute concrete 'this must change NOW" message, loud and clear. so well that like I said I rarely get past One.