I dont really like idol anime because they usually have nothing to offer except the music.
Even with Love Live which is the biggest series the music is usually very good but the rest of the show is lacking, the characters are not interesting, there is no story and so on.
But whenever a new idol anime comes out I will always watch the first episode because its the one where they put the best song and the biggest performance to draw in the viewers
For example in Love Live Nijigasaki
the song is godlike and the animation is really really good.
Same with Re:Stage Dream Days
https://youtu.be/2_Vx_xD1I5k?t=33https://youtu.be/2_Vx_xD1I5k?t=742Re:Stage Dream Days is doubly special because not only do they have 2 incredible bangers in the first episode, they are also just an anime made solely to promote a shitty mobile rhythm game
If you have any other examples of this phenomenon occuring please share