<With that said: people checking/answering their email or checking error logs at odd hours "for free" really do bring value to a company though.

I don't think of myself as having trouble with work/personal separation. I like my vacations, try to enjoy work trips, and don't feel obliged to work into the night.

That said, I tend to scan my email when on vacation or if I'm watching TV at night and, if there's something I can deal with in a few minutes or at least flag as "I'll get back to you next week," why not?