It seems there's a lot of these short (e.g. 3-5 minute long) anime series recently, specifically ones that air on TV (as opposed to ONA's). Shows like:

* [Fireball/Fireball Charming](http://en.wikipedia.org/wiki/Fireball_%28anime%29)
* [Chii's Sweet Home](http://en.wikipedia.org/wiki/Chi%27s_Sweet_Home)
* [Encouragement of Climb](https://en.wikipedia.org/wiki/Encouragement_of_Climb)
* [Recorder and Ransell](http://en.wikipedia.org/wiki/Recorder_and_Randsell)
* [Aiura](http://en.wikipedia.org/wiki/Aiura)
* And an older one, [Di Gi Charat](http://en.wikipedia.org/wiki/Di_Gi_Charat)

What started the trend of short 3-5 minute per episode TV series. How does that fit into a regular TV time-slot if it's so short?