Responses

They probably purchased the same 3D background asset in the drawing software they use (Clip Studio Paint I'm assuming). Like Shinz said above, it really makes the workflow faster as it can be placed and modeled however you want. ^^
But it's good to know that these wonderful artists need assistance like this as well :p
I've just noticed something. The apartment that the auther used for eunsung's house is exactly the same as the house dojin and hyesung has in love is an illusion, and kangwoo's house in K's secret. I thought I was just seeing similar korean luxury apartments lately.
BUT NO! they are actually all the same! From the chandelier, to the stairs, to he coaches and lamps. My eyes has been opened. I am a changed person
http://www.mangago.zone/read-manga/starlight_scandal/uu/iur_chapter-5/pg-12/
http://www.mangago.zone/read-manga/k_s_secret/uu/iur_chapter-40.1/pg-3/
http://www.mangago.zone/read-manga/love_is_an_illusion/uu/iur_chapter-93/pg-6/
I couldn't find a more wider detail of the living room and kitchen of dojin's house. but it shows a lot of details to compare with the other two