Naruto is synonymous with filler, but it also shows why filler isn’t necessarily a bad thing. The anime premiered in 2002, long before seasonal releases became the norm for successful shnen. The weekly-release format was initially popularized by Dragon Ball, and it dominated for decades. Some series like One Piece (which has surprisingly little filler) still use it. A weekly-release anime eventually catches up with the source material, and filler prevents resulting gaps in airtime to keep fans satisfied and willing to return. In the pre-streaming age of network programming, this was especially important.
