Upvote:3
There is always something going on but like mentioned typically less so on weekdays unless you are well acquainted with a local or maybe not foreign. I've seen some clubs in Seoul popping on a weekday but they were clubs for Koreans only. My general rule of thumb is, Thursday-Sunday is always a good bet. Monday and Tuesday can be a little less lively. Wednesday is a wildcard. But Mon-Wed there will still be some heads out. I want to say that there is never downtime when it comes to nightlife in Seoul. It could just be the places I've frequented.