Safety question

So we all know the four rules:

1. All guns are always loaded.
2. Never let the muzzle cover anything you are not willing to destroy.
3. Keep your finger off the trigger until your sights are on the target.
4. Be sure of your target and what is beyond it.

My question is this:
When is it acceptable to violate any given rule? For example:
A gun isn't loaded when it has a chamber flag in place. In SWAT training, we have our firearms inspected to ensure that they are not loaded, a chamber flag is placed, and no loaded magazines or ammunition is allowed in training. We then spend the rest of the afternoon pointing guns at each other for training. This violates at least two, possibly all four, of the rules.

Every time you carry in a shoulder holster, you violate rule 2. Can you violate rule two if the action is locked open? If not, then how do you put your weapon in the case? Approach the firing line? Attach a suppressor? If you have a firearm that has the action locked open, and there is no magazine in the well, is it a sin to sweep someone?

For rule three, how can you disassemble your Glock?

My point is that there are times when the rules don't apply. Where is that limit?