There is no concrete number of episodes/chapters/volumes where going over it turns something good into something bad. Anyone that tries to give an arbitrary number is just pulling it out of their ass. And the desire to limit how much content you think should be made for any given series/franchise just makes it seem like you don't like watching anime and want it to be over as soon as possible.
>>282939304 (OP)
Story driven anime should be over in 25 episodes, at most 50. Character driven anime can go for ever. Lucky Star should have had 1000 episodes.
>>282939378
Not OP but we always get shows with 24 episodes that always need a little more time to finish telling the story, so anything less than 24 is too little, but more than 40 is also too much, 36 seems around the right amount.
>>282939304 (OP)
You don't NEED more than 36 to tell a good story, but by going higher you can tell a grander scope story that is more fleshed out, such a story would be rushed if done in 2-3 cours