I use a pomodoro timer and find it is amazing at keeping me focused and makes you realise how long your spending on a simple problem.

At the same time, it's amazing to see how quickly 25 minutes goes, and sometimes it's a bit stressful to see the clock ticking down.

I don't track my time in a log.

My friend has a 25 minute timer, during which time, he only focuses on the task in front of him. It is more to curb ADD but ends up helping with productivity.