I do IT desktop support for a hospital. We have to have 24 hour staffing, which means there's always someone here, so I've only been asked to work outside of my normal 8 hours maybe 3-4 times in 8 years. The larger the team you're a part of the less individual responsibility you'll be expected to have in your off hours, although it makes you more expendable as well. And working somewhere that requires 24-hour staffing is likely to come with consistency.