Err, why would they not be able to teach the same class to a new cohort the next time it's taught? Yeah, it's a little repetitive, but how interesting can you

Err, why would they not be able to teach the same class to a new cohort the next time it's taught? Yeah, it's a little repetitive, but how interesting can you make intro-to-$SCIENCE. Profs, usually junior profs, have been doing this at uni for ever.