@Lori - I find half a day to be the *minimum* time I can set aside for deep work. Preferably a full day at a time. And best is two uninterrupted days. People wonder why I don't have time for a "quick" phone call, etc, they don't realize a "quick" call takes at least an hour usually, and disrupts at least a half hour before and after, which means they "stole" half of my deep work time if I allow it. I try to schedule all meetings on one day a week to avoid this. When I see all these younger startup founders going to "grab coffee", going to "meetups" and "hackathons", I'm not surprised when they don't make it. To make it in any creative endeavor means, first and foremost, say no to nearly everything except buckling down and doing the work.