My experience with this type of tracking is that it makes me more thoughtful about my time. I used Numbers and it cloud-syncs to most of my devices, I prefer this over passive trackers.

I did this for a month a while back, one realization I instantly had was that a lot of the my attention issues were caused by 'micro-interuptions'. For example, spending 8 minutes answering a support question on Slack and then going to write code - how do I record that? The same is largely true with Twitter or even HN, spend 5 minutes browsing instead of doing something with intention. Recording [Activity,Start,Stop] was preferable for me, the continuous scale made it really easy to track not just what I was doing, but the interstitial time when I didn't actively have a plan to do something.

Just setting out to record what I am doing helped to limit the number of things I was doing and made me be intentional about what they were. This post was relatively timely, as I actually started doing it again this morning.