Action shonen anime are extremely popular, with series like Naruto and My Hero Academia having huge fanbases. Even non-anime fans probably know about those two shows. As action-packed as they are, the episodes also come with plenty of character development and slow periods, which may not gel well with every anime fan out there. These moments may be important to add more depth to the personalities on the show or explain certain powerups and how they come into existence, but it comes at the cost of the viewer possibly losing attention and moving on to another show.