The tool is launched on boot via launchctl on OS X and runs all the time. (https://developer.apple.com/legacy/library/documentation/Dar...) It automatically deletes screenshots older than four days. I use it in conjunction with Workflowy and a web app I wrote called Task Ranger (http://taskranger.com) to keep track of how I spend my time and to come up with improvement plans.

Task Ranger gives me the big picture -- e.g. learning new things is my biggest time sync and takes 25% of my working hours. The screenshots + workflowy give me the micro level view -- e.g. studying unfamiliar codebases is 1/3 of this 25% timeslice.

So now that I know learning new codebases takes a lot of time, how can I get better at that? Well one thing I've started doing is creating a txt file containing basically a manually generated tree of the function calls made by a program. It might look something like this:

    /new_user
      validate_form
      create_new_user
        User(...)
      send_welcome_email
        load_email_template
        pass_to_email_service

That's a toy example of course -- real-world call trees are huge. After I generate this once I can quickly see how the whole program fits together. And I can use it with this feature in Sublime Text where you right click on a function name and then pick "jump to function".

That's just one small example of something I'm trying. It's an ongoing improvement process that I try to allocate time for. The screenshots are just a helpful view toward understanding where my time goes in more detail.