I don’t get why people think 996 is even optimal for productivity in the medium or long term. If I work hard past 8pm I can’t sleep - my brain is still whirring. That results in worse sleep -> less memory creation & skill consolidation -> lower productivity.
In my mind, if you cared ONLY about productivity in the medium and long term, you’d probably do something like 9-7-6. So you still get a day off, and don’t work past like, dinner time. Still give yourself time to exercise, still give yourself time for social interaction, sleep can stay dialed in. I think someone doing 976 probably out-competes someone doing 996 in short order.