Very little. Kids and wife dont use computer at all. I use it for work and HN (currently HN whilst waiting for compiler!). We have one smartphone but it's rarely used unless commuting.
I've heard of a few parents who have gone TV free but allow their kids phones, iPads and laptops for homework, etc. End result, they see less of their kids because they're all in their rooms watching streaming TV or videos.
Results may vary of course