I like how the book The 4 Disciplines of Execution describes this: they call this the Whirlwind aka the operational, day-to-day stuff that is really important. They say your day should be 80/20 between this operational stuff and strategic stuff or core goals. The 80 keeps the lights on, the 20 improves the state of your art. This translated to 1 day a week which I like to call no-meet-mondays.