Sorry to hear it didn't go well for you the last time. I know a bunch of people who passed the interview process only in a later try.

I personally do 9-6, take my coffee breaks really seriously, sometimes to later work like reply to messages if I'm in the mood, and never (save for very very rare shitstorms) work on the weekend.

Teams vary, I've seen plenty of 9-5ers that make it work (some of them on my team). As you already pointed out, I also think younger people tend to overwork, and people with kids tend to reprioritize and go for a 9-5 schedule.

Since one gets to choose the team they join in Facebook (in contrast to being offered a job in a specific team) you get to choose a team that will fit your personality. This means you should pick a team not only based on their project, but also based on the people and the team's culture, and if you pick wrong, you can rather easily switch.

I'll back up what strulovich said. Every team is different, but most folks on my team are in the office from 9:30-6 or so. Some come in earlier, some come in later. I'm a parent and on a train commuting schedule, so my day is 7:45-5:15 or so.

You can get PIPed out at FB, but in my org it's very, very, rare. Out of 100 people, only a few people received a rating that was less than "Meets All Expectations" and none were in danger of a PIP.

Regardless, people are measured by the work they do and against expectations of their level. There is no "hours your butt is in a chair" requirement. The big caveat is that some teams are more hectic than others and quality of managers may vary.

I do 6-10 hours per day, depending on the day. My team has quite good WLB. I have heard of other teams that are more pressured, but haven't spoken directly to those teams.

Compared to my previous... 4 jobs (+1 company founded), this is the 2nd lowest stress. The one lower stress job had 1/3 the compensation, no career growth, and was just a "marking time" federal tech job. YMMV.