Not only that, in some places there is even a second and third departure waiting queue like in Ginza Line in Shibuya. People do wait there on rush hour not for

Not only that, in some places there is even a second and third departure waiting queue like in Ginza Line in Shibuya. People do wait there on rush hour not for the next train, but for two trains later (same train). The justification is that it is the beginning of the line, and if you wait 3-5 min longer you'll be able to sit for the whole trip.