26 episodes is the ideal Anime structure

I'm not saying this is universal, if a story only needs 12 episodes that's fine.

And also not all 26 episode shows even use the structure I'm thinking of.  There are two main ones that do.  Noir, my absolute favorite Anime, and Witch Hunter Robin.

For both of these shows, the first about 10 episodes are purely Episodic and self contained, Monster of the Week in the case of Witch Hunter Robin, and Mission of the Week for Noir.  With minute if any hints of the over arching story-line.  And to me that is how it should be, build up and invest us in the characters and world so that we'll care when they get drawn into a more epic story later.

Then around 11 and 12, the over arching plot-line starts becoming more present, but maintaining the basic Episodic structure.  Then the prevalence of the main story builds and builds until the last 7, 8 or 9 episodes are basically one big movie split into pieces.

I think Noir's sister series Madlax was hurt a little by abandoning the self contained format too soon.  I really would have liked to see more exploration of the jumping back and forth between effectively two totally different genres.

I'd like to see a Magical Girl show use this structure.  We usually only get 12-13 episode Manga adaptations, or 50 episode monstrosities.  And then the darker Magical Girl shows use the 12 episode structure.