I second Aoi Honoo and Okashi no Ie. Aoi Honoo especially for Yagira Yuuya, who I think is hilarious in it.
Didn't look at your completed list and just briefly skimmed the list of suggestions, so I'm sorry if I repeat some already-mentioned titles:
- Ito-kun A to E
- Karamazov no Kyodai (35-ish minutes, I think, though...)
- Limit
- Dias Police
- She / シー (2015)
- 49 (except for the last ep)
- Piece
Some of the above is closer to 30 minutes. Other stuff I haven't seen:
- 4-go Keibi
- Oniichan, Gacha
- xxxHolic
- Tokio
Any asadora as well. The episode counts are long but each episode is no more than 15 minutes.