We are very much a dev ops team. As such, our work does not necessarily end at 5 pm every day. We are the engineers, customer support, QA, and often times part-time business analysts working with management to define requirements and make the business value pitch to the stakeholders.
Bottom line, there isn't really defined office hours and we often put in a great deal of time outside the office. While that may be a con for a lot of people, the team we have accepts this as a welcome challenge and often goes above and beyond in order to make the company successful.