Actually 'leave it' can be taught in a matter of minutes, and 'drop it' doesn't usually take much longer. It really just comes down to clear and effective communication - so long as your dog respects you. If you observe dogs interacting they are very clear about their intentions and can get the message across very quickly and effectively for the most part - sometimes with just eye contact and body language.
We have 'relationship drills' that we do before we do anything in order to ensure we have the relationship in balance first - this sets us up for success from the start.
Dear Schwinn - I love your sense of humor. Thanks for the laughs