Not to the extent you are referring to. Sure, we may use the gear if we receive a last minute change due to ATC or weather and we have to immediately rush re-configuration to satisfy a new altitude change (to where changing prop settings or speed brakes won't be enough), but if you are having those issues when are in the middle of descent from cruise and brushing up against a 250/270 Knot limit, than something has gone rather wrong. I don't know anyone that has ever had to get as drastic for drag as extending the landing gear all the way out on a STAR.
On another note, the landing gear is allowed to be extended into high mach speeds because it is used as a sole and last resort for drag in high overspeed situations, as you obviously can't be extending flaps or speed brakes at high mach - landing gear is the only option for drag at those speeds (and yes, you'll blow the gear doors off).