Pick the corridor first
One beauty street a day: Myeongdong, Hongdae night, or Garosu / Apgujeong — pick one, finish, stop. Do not stack two. Wholesale is Dongdaemun. Souvenirs are Insadong. Dosan and Cheongdam replace the Garosu-gil day: the avenue to Dosan, then stop. Do not also open Seongsu or Jamsil, and do not stack Garosu onto Dosan–Cheongdam. Seongsu is the warehouse lane, the shoe street and Yeonmujang, then Seoul Forest — not one café and out, not a mall, and not a Myeongdong beauty extension.
One mall
One mall only among three: COEX (Samseong), The Hyundai Seoul (Yeouido), Lotte World Mall (Jamsil). That mall is the indoor axis for the day. Do not walk all three, and do not add Garosu-gil, Dosan–Cheongdam, or the Seongsu lanes.