Another fair point! The truth is, everyone’s ‘high energy’ is a little different. What my period of high energy is could be very different from yours. Its highly personalized hence we would require the user input here, what they think works best for them. Get their feedback on their energy levels through the day (asking them few times a day) and then sort of predict their high-productive hours for them to schedule their most important work during that time. Let me know if this sounds stupid or if it makes some sense.
You should try making an app for yourself that pings you periodically about your energy level and gather a few weeks worth of data and see how it goes, that's what I think. I guess that's an issue for an app that would be used by many -- it would take a serious commitment from somebody to collect enough data to be useful.
Yeah i see what you are saying. Will try to figure out if we can manage a basic version initially with as less data from user as possible yet still being effective and valuable to user.