Unlike Les (a local friend of mine I mentioned), I myself am not very conscientious, but I'm a very _slow_ grader all the same (I loathe this part of work, & I don't like teaching composition courses, mainly though not solely because my department demands that I require two revisions for each assignment & that I assign four 5-page papers per student in a class of 24 students!). Generally speaking, though, I suppose adjuncts can cut corners (making few comments on papers; always using the same textbooks, lesson plans, assignments, etc.; and so on), which doesn't cause any immediate economic problem unless a student or an administrator complains.
It will be interesting if someone undertakes a time-use study of college teachers of all ranks.
The thing is, though, that if one is to be an adjunct who mainly teaches so-called "service courses," she *doesn't need* a Ph.D. (In fact, since so many "service courses" are already being taught by grad students, one might argue that you only need a bachelor's degree to teach undergraduates; at the Ohio State University, the Department of Mathematics even allows qualified undergrads -- who don't have to be math majors -- to teach a good number of courses!) What's an an economic incentive of pursuing a Ph.D. if you are much more likely to become an adjunct than a tenured full professor?
More importantly, what's a political justification of the tenure system (part of the hierarchy)? After all, the thread "reparations & exploitation" came to center on an ethical & political justification of pay differentials (or lack thereof).
Yoshie