Dragon Ball Super had a 4 year gap between the Broly Movie and the new CGI movie being released this year. Long gaps happen. I don't even know why people are complaining in this instance since the turn around time between Eternal and Cosmos is smaller and we know when the films are getting released. Talk to Madoka fans who still don't even know when the new Walpurigs Night movie is being released and the story has been in a cliffhanger since 2013... 9 years ago.
I don't think it's just "the gap', it's the timeframe for an already completed manga. Even as the above case mentioned with shows like Initial D the manga was still ongoing. Both Dragon Ball Super, including movies and Puella are essentially new stories/content in the making. As far as I know Puella didn't start out as a manga, so I don't know if it or DBZ are still ongoing mangas or the animation is being adapted from these ongoing mangas.
Sailor Moon manga has been finished for eons. The original anime had 200 episodes and 3 movies that all fell in line one way or another and took 5 years.
Crystermos has a fraction of that and by the time we get to Cosmos it will have been 9 years...and depending on your country and how they release it... probably 10 or 10.5 years.
So my question was, has there been an anime with a completed manga (old work) that took this long to get through to reach the closing of its run?
Initial D has 48 volumes.
Sailor Moon has 18 or less.
They haven't taken the initiative to adapt any of the side/short stories of Sailor Moon in the new era either.
And this isn't a bash Crystal post as I still like it...just some chatter.