Work is a spectrum between specific repetitive tasks and the need for deep creative solutions to problems. On one hand we have the need to pull this lever every 36 seconds. on the other, is The Problem. We've all faced The Problem, but perhaps not for work. It's the thing that's at the top of the stack for days, weeks, or months on end. Perhaps solving a Rubik's cube. Perhaps understanding recursion. We've all gone through that phase of not understanding something and thinking about it constantly.

IMHO, the 9-5 is is useful because, in the pull the lever case, the lever gets pulled. More importantly, a substantial fraction of time exposed to The Problem. You have nine hours to kill, odds are good people will spend those hours possibly getting hooked on solving The Problem. There's little chance they'll solve the problem in those hours, but they'll get hooked on The Problem and think about it while washing dishes, in the shower, and sleeping. Once you're hooked, it's tough to get away from it without solving it.

Ultimately, i think anything repetitive will be automated away. But we still need some way to hook people on The Problem. Hours and hours of exposure is probably inefficient, but it's effective.