What is the point of including a recap episode after just 12 episodes? Anyone who's been watching the series knows what has happened, there is no need to include it.
The simple answer is obvious, we don't all have the luxury of the Internet. In Japan, anime episodes are airing weekly so there is the possibility of entering the series half way through. While the series is still airing, you can't go out and buy the DVD or go back in time to when it was airing. So to remedy the situation, a recap episode will sum up the entire arc's main points.
The other reason is because the next episode was not suitable for TV. For whatever reason it is: violence, sex, controversy or
|Nice boat is nice|
What makes a good recap episode? Usually we have a simple narration from one of the characters. There has to be something that makes you watch it or you're really just watching 12 episodes in 25 minutes. If you felt like it, you could just watch recap episodes instead of the series.
Comedy is a nice addition but it might not fit well with the themes of a series. When it does work well, it can lead to a decent recap. I particularly liked Moetan, it had Sumi and Ruriko giving us something very similar to a directors commentary. The commentary gave us more than just a simple recap. I'm unsure why they skipped an episode and replaced it with a recap, but we are given the reason "hype up sales for the DVDs".
Although it isn't anime, Avatar: The Last Airbender had 2 flashbacks during actual episodes. The first was when Aang was clearing his chakras and the second was a play parodying the series in the form of a form of a play. When clearing his chakras, he had to remove his blocks. To do this, he had to let go his past and move forward. The play showed all the most important parts of the series while applying a comedy aspect. It was a parody that made fun of the whole series.
I would love to go back and watch a series I saw a few years ago, but I don't have the time. Not every series has recaps, but for the ones that do, 25 minutes to rewatch an entire series is better than 300 minutes. The only problem with this is that you miss out on 275 minutes worth of content.
Explaining something is a given, The ending of Clannad was confusing, It wasn't obvious what had happened. But with the recap, everything was explained in the simplest way possible. Even with the confusing ending, it doesn't change my 10/10 score.