There aren't many hard-and-fast rules of time management that apply to everyone, always, regardless of situation or personality (which is why I tend to emphasise general principles instead). But I think there might be one: you almost certainly can't consistently do the kind of work that demands serious mental focus for more than about three or four hours a day.| Oliver Burkeman
The “magic ratio” is 5 to 1. For every negative interaction during conflict, a happy relationship has five (or more) positive interaction.| The Gottman Institute