I don’t think it’s one size fits all. Carmack mentions some people just have 7 good hours in them a day. But you can’t just think in terms of day by day, even f

I don’t think it’s one size fits all. Carmack mentions some people just have 7 good hours in them a day. But you can’t just think in terms of day by day, even for the same person: Sometimes I have 60 good hours a week in me, some days more or less than average to get there. I’m obsessed with an idea, driven to complete it. And sometime I’ve barely got a solid 15 hours in me for the week, maybe for multiple weeks at a time. No simple answer for what leads me there, but the rest of my time is spent working on the absolutely more urgent things that can’t wait and then just trying to fill the other hours with things that aren’t completely useless, learning about current tech trends, trying to find something “shiny” to strike my interest that has at least minimal relevance to my field, etc. I’m sure that averaged out my workplaces have received the value they paid for in my salary, but there’s peaks and valleys. And sometimes that even includes having a “screw it” day where nothing critical has to get done and I need a mental breather, time to clear my head from the day to day. But that’s just me. Everyone will be different. Trying to make a universal paradigm of optimized productivity is a waste of effort. The best you might get are some general guidelines and enlightened flexibility.