I check Facebook in the morning, occasionally throughout the day, and sometimes in the middle of the night. The reason for those check ins is because I belong to a neighborhood group, and I check in to see what's going on, particularly if I hear a lot of dogs barking, hear unusual activity, or hear sirens. I also help manage the 'crime and emergency' type page for the neighborhood, so will go on there to share information from the local police departments and severe weather type announcements. Other than that, I occasionally post to my shops' Facebook page, and chat on occasion with friends, although it's mainly just mutual Liking of posts.
I have several Twitter accounts, and am often on and off of them throughout the day posting from my shops and sharing those marketing posts among my other accounts. I also do the social thing on the accounts to share information relevant to my followers, RT some of their posts, post some fun and interesting things, and also to keep up with or share my opinions on certain things, such as favorite television shows.
I post to tumblr now and then. It's a shop account, but I have a sort of rapport going on with some of my mutual followers, even though we don't actually converse. It's pretty much the same with Instagram, although I post there more, and follow a variety of related accounts, as well as animal accounts, nature themed accounts, Foodies, home and garden sites, etc. Pinterest I mainly use for recipes, DIY, decorating tips, crochet patterns, and also to share not only my items I'm selling, but also to sprinkle some love on my Twitter followers' items they're selling and promote their shops.