No longer than it takes to twist a primer pocket clean, why in the world wouldn't you do so. I have done side by side test and Boyd is right. There is no difference in accuracy. My way of thinking is this. This step of the reloading process takes little to no thought, and little to no time, and it sure doesn't hurt anything. I keep mine clean, as well as the case necks. This is just me though. i keep everything clean! This stuff cost to darn much not to. Lee