Within the military, there is a degree of accountability for firearms cleanliness that no one person could ever do on their own. There are situations coming to mind, such as, You are the armorer in a unit that is switching out M-16 A2s for new A4s. So you go to the depot to switch them out, and their guy looks your weapons over and says; "I can't accept these weapons, they're dirty." They weren't dirty enough to make them malfunction or harm them in any way, but this guy's policy says that all weapons he accepts for turn-in must be clean. Not mostly clean. Not 'clean enough'. CLEAN. Common sense has no authority over written policy. This means that the guy doing the turn in has to either clean them all RIGHT NOW, or take them back, set up the paperwork and appointment for the turn-in all over again, and get a ten-man detail from the first sergeant to clean them all. And when he goes back, you know the guy accepting them is going to give them even MORE scrutiny than he did the first time. This creates a culture where no armorer will ever let a non-pristine rifle back into the arms locker.
When your unit goes to the range, you will be spending a few hours cleaning. Period. (And blanks are dirtier than regular ammo.) You might be an expert in cleaning and get done first, but if you are the first guy to try to turn it in, they will dig with their pinky until the find some black and give it back to you. If you go in at the END of the night, everyone wants to go home, and they are much less careful. Don't be the first guy in line to turn it in.