[mjn]

It's a bit more than six courses a year at community colleges and teaching-oriented 4-year colleges (though you're still right that adjuncts are much cheaper). In California, most full-time faculty at community colleges have a 15 credit per semester teaching obligation, which works out to ten 3-credit courses a year. Some do get credit in lieu of a course for taking on other responsibilities (dept chair, director of a program, etc.), but that's the baseline workload. Even the Cal State system, which is made up of 4-year schools, has a baseline teaching load of eight classes a year ("4/4").