I shoot it whenI can't find anything else. I was scared away by all the horror stories of steel cased ammo at first also. But then a friend who collect ammo showed me a box of U.S. military ball ammo made in 1943 and it was steel cased. Seems that brass was in short supply so they made steel ammo in .45, .30 Carbine, and .30-06. If it was so terrible and hard on weapons I doubt that they would have used it. The steel in the ammo is softer than your guns internals.
So no I don't shoot it alot. But if it comes to only having Monarch steel for practice or no practice I have no problems shooting it. I've had a couple of hundred rounds through several of my guns and no problems. And yes it does make the gun smell. So I scrub it down a little better.