I'm a software engineer at Google in Seattle. I try to get in by 8:30 but sometimes it's closer to 8:00. I leave between 5:30 and 6:00 depending on when I got in. The office empties out pretty quickly in the evenings.
I almost never work longer than that. (I honestly wish I could sometimes. I end up having to interrupt myself in the middle of things to leave on time, but such is life when you have kids.)
If he's also doing a bit of email in the evenings, leaving at 4:00 doesn't seem unreasonable. I've never seen or heard anyone fret about work hours at the office. My experience has been that the company is very results oriented.
(This is still hard for me to adjust to coming from EA where I worked a lot of hours and company culture, unintentionally or not, placed a lot of emphasis on how long you kept your seat warm.)
If you're "in the groove" so to speak with coding, continuing work could be much more productive. At the times he wishes to work later, his additional work could be dozens of times better than a typical day. In contrast, coming back to code you were in the middle of a day later can have an hour of delays as you work just to get back to the state of understanding you had before.
In this way he will produce more. Producing more sometimes leads to earn more (that one's not as definite). Learning more... well, the more projects you complete the more you get to do; the more chances to learn.
This isn't to say that having a fixed end time is bad, just that your statement is false.
The statement isn't necessarily false. You didn't show how the statement is false.
More time spent staring at a text editor (or even spent pounding on a keyboard) does not mean that you produce more. Maybe if your production metric is characters typed you produce more, but in terms of usable features there is going to be a point of negative returns on time spent.
I think he means that when you are in a really good groove, you can be way more productive (and happy to keep working).
I don't know about anyone else, but I can definitely relate. This is 100% about your state of mind.
Happy code comes from a happy coder :)
I'm definitely more productive if I can park tasks when I reach a natural stopping point and not have to abort right when I'm in the middle of my flow.
I don't at all think my long term productivity increases if I work more than 40 hours a week, but I think it would increase if I could be more flexible (just +/- an hour or two a day) about when those 40 hours happen.
I almost never work longer than that. (I honestly wish I could sometimes. I end up having to interrupt myself in the middle of things to leave on time, but such is life when you have kids.)
If he's also doing a bit of email in the evenings, leaving at 4:00 doesn't seem unreasonable. I've never seen or heard anyone fret about work hours at the office. My experience has been that the company is very results oriented.
(This is still hard for me to adjust to coming from EA where I worked a lot of hours and company culture, unintentionally or not, placed a lot of emphasis on how long you kept your seat warm.)