I've said elsewhere that one of the things I like about Instagram is that it's a place to put all the images which don't belong anywhere else. Too random for Facebook, not relevant for clients, and neither suitable nor strong enough for my portfolio. But worse would be to leave them on a hard-drive, forgotten in a cupboard, forever. While browsing my IG feed, I noticed that a great number were shot while I was waiting around for something.
It's an interesting category. These are the kind of images which, most of all, should fall between the floorboards. These shots are either an afterthought or noticed when you're thinking of other things. They're the result of time spent idle, with no planning or prior intention, and they wouldn't exist but for the opportunity of a few free moments.