The differences of music releasing between Japan, Korea and China/Taiwan

[Maemi]

I'm sorry if this has already been posted, but I just can't find a thread like this
Anyway, I'm very curious and I hope someone can explain me...

I'm cognizant when comes to Japanese releasing of music. I know they have their Orican chart, and that they always release few singles before album, to support and increase their sales.

But I've noticed that they release only digital singles in Korea, including mini albums, and of course full albums.

In China / Taiwan I can't see any singles released from popular artists, for an examle - Jolin Tsai.

Am I wrong, because it's impossible for me to know all artists' discographies, but that's just smth I noticed, so I want to check it. Why is so?