Yes! The one you created.
If you're already working 4-5hours a day (as in actual working) you are giving all to the company. If you answer silly mails or check Reddit or whatever the other 3 hours is actually not a big deal and not a big dip into your productivity. Not a black hole by any means.
If you think otherwise you are not only being "dumb" (compared to the "street-smart company"), you are being an economical irrational agent, so you will naturally be taken advantage of and get worst (not better) returns (not only money, things, like health, free time, meeting a SO, raising a family) in the long term.
The fact that you willfully go to that extreme only shows how toxic is the Calvinistic worldview implanted in many people in the anglo western world and how companies ruthlessly exploit it.
If you think otherwise you are not only being "dumb" (compared to the "street-smart company"), you are being an economical irrational agent, so you will naturally be taken advantage of and get worst (not better) returns (not only money, things, like health, free time, meeting a SO, raising a family) in the long term.
The fact that you willfully go to that extreme only shows how toxic is the Calvinistic worldview implanted in many people in the anglo western world and how companies ruthlessly exploit it.