When and why did the trend of 1:30-long openings and endings begin?

Question

I've started to notice lately that the vast majority of anime (that I can find, anyway) seems to have opening (OP) and ending (ED) sequences which are 1 minute and 30 seconds long.

Some examples (though I'm sure there are lots that I haven't covered):

• Fullmetal Alchemist: There are 5 OPs and 5 EDs, all of which are 1:30 long.
• Digimon Tamers, Steins;Gate: Both OP and ED are 1:30.
• GaoGaiGar and Neon Genesis Evangelion: The OPs are 1:30 long, though the EDs are only 1:00 in duration.
• Cardcaptor Sakura: The OPs are 1:30, did not check the ED durations.

There do seem to be some exceptions (again, far from an exhaustive list):

• One Piece: Though some episodes fit this pattern, others have 3-minute OPs and no EDs. (The combined duration is still the same, though.)
• Akagi, Kaiji: OP is shorter than 1 minute.
• Ga-rei: Zero, Aria: During the OP or ED music (which is 1:30 long), things unrelated to the OP/ED sequence happen (like actual parts of the episodes).

These lists are just examples of each, and don't really show that the vast majority of anime (I would wager 90% or higher) seem to follow the 1:30 OP/ED "rule".

It is worth noting that most American series have openings which are 30 seconds or 1 minute in length; Family Guy and the Sonic the Hedgehog cartoon are examples of this, though there are far more.

When did the 1 minute 30 second duration of OPs and EDs start to come into popularity, and is there a particular reason why they did so?

Answer 1

This article here explains very well why Anime OPs are so long in the first place.

To summarize a few of the points:

• Cost
• Spread out commercial breaks
• Advertisement for record companies.

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Cost:

• Each episode is a total of 25 minutes, which leaves 5 minutes for commercials in a 30-minute time slot.
• Furthermore, OPs and EDs are typically reused for most of the episodes in a series.
• OPs and EDs only need to be animated once.

So the longer you make them, the less work you need to fill up the rest of the time. Therefore, long OPs and EDs cut down on production costs.

Spread out commercial breaks:

To quote the article:

Typical anime television episodes broadcast on network Japanese television have commercial breaks after the opening animation, in the middle of the episode, and just before the ending credits. With this broadcast pattern, a 90 second opening puts more content between commercial breaks than a 30 or 60 second opening, which may be less annoying for viewers to watch.

So this is more of a reason with the flow and pacing of the episode.

Advertisement for record companies:

Again from the article:

Opening animation sequences serve as record company advertisements. A popular opening animation sequence like that of the Suzumiya Haruhi no Yuutsu or Lucky Star television series can make their series opening theme songs turn into overnight smash hits. A longer opening animation sequence provides time for the theme song to get exposure and gain popularity.

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Getting back to the point of why 90 seconds, that seems somewhat of an arbitrary number possibly the result of a bit of trial and error from the industry.

As the article mentions, they used to be 60 seconds back in the 1970s. Then they were increased to 90 seconds for the reasons above. It's possible that some studios experimented with even longer OPs/EDs, but later on, found that 90 seconds was a sweet spot.