Short-form anime (or tanpen anime, see Is there official terminology for anime series that run less than the standard length?) are relatively common, with at least a few each season.
It seems strange to me that this would be a worthwhile investment for studios. Sure, the production costs will be lower, but there are certain overheads that aren't going to scale with cost, and their DVD sales will surely be lower. So it seems like a losing deal for studios.
Why, from a production standpoint, would studios decide to produce short-form anime over a full-length TV series?