My answer at this very moment in time is around 1/3. Which seems a lot. Though these projects have been less about automating drudgery and more about unlocking

My answer at this very moment in time is around 1/3. Which seems a lot. Though these projects have been less about automating drudgery and more about unlocking new workflows and ways of understanding things. When I first started working at my job I sneakily built a suite of tools for visually working with NL grammars (instead of just buckling down and writing the grammars). Although I don't maintain it anymore, it's now used by an entire team. It was great that my then-managers saw that I was on to something and let me obsess about it for a few weeks. I recently spent a few weekends writing static code analysis tools to analyze our codebase. There is some pretty exciting stuff that can be done there. It hasn't paid off quite yet, though I know it will. Another project I've been juggling with my 'official job' is a nice new logging system with all kinds of cool features. There are so many challenges about making a piece of infrastructure work technically and culturally across a large team, however. It's much easier to estimate how long the technical part will take. I've also written a bunch of tools that just failed to find any real use. In retrospect, these were mostly vanity projects of some kind, whereas the projects that have worked have always been about scratching an itch that I can see other people have (whether or not they articulate it).