I use it, although I admit not religiously. Writing down my tasks I need to get done, then 'estimating' them in 25 minute chunks really helps me get my brain around the concept of time, just how little of it I have in a workday, and just how fast it passes, which is the real issue for me.

Also, there's nothing wrong with doing 2 or 3 in a row, if you feel like it.