I think like the quality was worse since season 3. This season is still good, but I joined the fandom in season 4 and I binge-watched 3.5 seasons in like a week and I remember I was a little bit bored in season 3, I think 3x04 was especially boring? I don't even remember this episode very much, but it was always on my list of the least fave episodes.

But I think like the biggest mistake, before going back to Lima in season 6, was introducing newbies in season 4 as main characters with so much screen time, plots etc. To this day, I still don't understand how the creators were thinking this was a good idea? People loved the "old" characters, but suddenly some of them are not even in most of the episodes, Rachel and Kurt have like 5-10 minutes per episode, and even originals like Artie and Tina don't have a time to shine in the glee club. I understand they needed more characters, but why giving them so much screen time? Why not focus much more on "older" characters, why not have the new characters only in the background?

I think like giving so much time for Lima and the newbies was a big mistake. And instead of finishing the school year and saying goodbye to Lima as soon as possible, they did the longest school year ever.