It all depends on need. The idea that everything needs to work the same way is unsound. Arguably, the company I work for doesn't need to bring everyone into the office every day; we seem to be doing quite well. Another firm that believes it sees better creativity when people are in the same physical room may be better off not having their workers be remote.

And like you say, not every company necessarily gets a benefit from having an 8 hour day. Depending on the nature of the job, the remaining hours of the day can be a diminished return, in which case one might as well give up on the game of charades and just allow their employees to go home.

I think the idea of measuring productivity by hours spent is absurd.

I manage my teams by tasks accomplished. I really don't care if they were able to complete it in 2 hours and take the rest of the day off.

I simply acknowledge formally what happens in practice anyway. The average "8 hour workday" only contains about three productive hours [1].

For me, it varies wildly. Some days, I'll get in "the zone" and 12 hours / and thousands of lines of code will fly by. Then I'll spend the next day or two in a brain funk waiting to recharge.

I've learned to embrace my "bursty" productivity patterns and to structure my delivery expectations around them. If I get trapped into a X number of hours per day butt-in-seat situation, my overall productivity declines sharply.

[1] https://www.inc.com/melanie-curtin/in-an-8-hour-day-the-aver...