There are some rules that we follow to keep us honest, to make sure we stay safe and to make sure we do not become a nuisance.
All the other times, Rugby must be in heel position, on a sit or down stay, coming to me from a stay position, or he is being sent away from me. I send him away for two reasons - to retrieve something, and to use the bathroom. Being able to direct where Rugby goes without using a leash means that he is more under control off-lead than most of the other dogs are while on-lead.
Rugby is also not allowed to visit other people or dogs without permission. It is not safe, and it is rude. He sometimes complains about this rule.
These rules apply to other dogs that I work with as well. They are usually not as well trained as Rugby is, so I have one more rule to add. If a dog I am responsible for is not trained well enough to follow these off-lead rules, I will not be walking them on equipment that they can back out of or break free from.
Rugby spent a lot of time learning this vocabulary and learning to make decisions for himself (learning to say no to distractions) so that he could enjoy these off-lead privileges and opportunities with little concern. Now I can't imagine living with a dog that didn't have his vocabulary.