In short, in July peak season in Seoul, Daejeon, and Masan, is it necessary to book cheap accommodation (20,000 won a night or less) in advance, or is it easy enough to find a place at short notice? I can go up to 40,000 for the odd night if I have to, but I'd rather spend money on doing something fun than too much going on accommodation.
I'm going for 11 days to Korea to see friends as part of a bigger trip to Asia. Mostly I'll be in Seoul, but I'll spend a few days in other cities. I'd prefer to have the flexibility to decide what days I go while already in Korea.
I'm also happy to stay in jjimjilbangs and pack reasonably lightly that my stuff will all fit in their lockers, but I'm just not sure how easy it would be to drunkenly stumble into one alone after a night of drinking with friends. Any thoughts from people who have done this?
19-year-old Australian male who's made a similar trip to Korea before, by the way. Just never been in the peak season.
Any thoughts or tips are greatly appreciated.

