We use my Three pounder for ceremonies, living history demonstrations, and reenactments.
At NPS sites we are required to wait 10 minutes between shots. This is no problem since we are doing interpretation to the public between shots anyway.
We did a three gun salute during a War of 1812 vet's grave marking ceremony recently. We did not "wait" between shots, but did go slow and methodicaly to make sure all safety steps were adheared to.
For reenactments, the wait is based on the needs and flow of the battle. We don't wait but take our time during reloading. We migh might aveage two shots a minute at one point, then one shot every 5 miniutes later.
Wait time is not nearly as important as insuring that the bore is searched (wormed) between shots to extract all the aluminum foil, and that the bore is properly sponged. If the vent is thumbed and sealed properly and the sponge is damp and fits the bore right, there will be a very audible hollow sounding "thump" when the sponge is withdrawn from the muzzle. If we don't hear that, we responge till we do.
We shot 25Lbs of powder during our last reenactment.