Never flown the Challenger itself, but have flown three of its derivatives (CRJ-200/700/900). For all three of them, partial or no-flap landings were practiced in the simulator regularly. Just as well, because the -100/200, for example, had a habit of experiencing flap failures, while on the -900 I had one case of a slat failure. Furthermore, for all of those aircraft single-engine landings are made with Flaps 20, which is also the case for landings with a pitch trim failure.