What do people do all day?

One question that has stuck with me recently is "What do people do all day?". My work habits don't fit neatly into the standard 9-5 office job (which is why I'm interested in the startup world), and my conversations with others have led to a somewhat bizarre conclusion and would love the input from others.

This is primarily about office type jobs, but the answer I have stumbled upon appears to be "not a lot".

This is not a dig at anyone or anything of the sort, from what I gather is that many companies operate with a tremendous amount of "slack". The processes which employees use are not optimised, and often they don't wish to have them optimised out of the concern that it will change their job too drastically. Additional the human parts, e.g) Kate can only do this task after James has done this one, add "slack" between these processes as the communication of the first task completion isn't automatic.

I am not a productivity zealot or anything of the sort, and am a work to live kind of person. But I would love to read books/other sources where the evolution of companies/organisations is analysed through this lense. I can understand the immediate reasons for several aspects, (stress reduction / breathing space / not wishing to work) but a systematic analysis would be very interesting to read, as understanding this would possibly enable us to work fewer hours and have more time to do other things!

Would love any input!