Both you and comment parent might find this interesting: A few years back a friend and I designed a web-app that had as its core difference the ability to automatically schedule all of your tasks (based on estimated workunits / pomodori and deadlines) around all of your existing appointments and free time. At its core, it could answer the question: "What should I be working on now?" -- but it could do this in about 1 second (that's how long the solver took) for the coming 3 months. You could redo this analysis every time anything changed, and it would present you with a new 3 month planning. We didn't get any further than (working!) prototype with 30 beta testers.
If you're interested, here's an extremely short write-up of what happened: http://timescapers.com/2016/02/07/timescapers-and-timerank-r...