from what i've seen, most people work 10ish to 6ish under very relaxed conditions like eg a comfortable lunch and a few breaks during the day. i've also noticed that people tend to be available online outside of their work hours, but nobody really expects that nor gets mad when someone isn't.
this was true for all of our employees when i was CTO/co-founder and also for us founders most of the time. this was also true when i worked at a Series A startup and it is true in my team at Google, and it seems it'd be similar in most other teams, too.
note that i'm not taking a stance on whether what i described above is good or bad, it's just what i've observed.