I need to get better at heeding this time management advice: "it pays to use whatever freedom you do have over your schedule not to 'maximise your time' or 'optimise your day', in some vague way, but specifically to ringfence three or four hours of undisturbed focus..."
The three-or-four-hours rule | Oliver Burkeman
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.
oliverburkeman.com