Most of the Hum and Sosc sections at Chicago (not sure about CIv) are taught by non-tenure-track faculty who teach two sections a quarter. In university terms, that’s pretty much a full-time teaching load, and it certainly precludes other full-time employment. It’s not showing up for an evening seminar once a week and telling war stories about your career. Unlike tenure-track faculty, they aren’t being paid to do original scholarly research . . . but if they ever want a tenure-track job, which most of them of course do, they had better be doing that.