in my department, we have 3 levels of calls...priority 1, 2 and 3...most black and white calls will be the extremes, absolute non-emergencies and no injury accidents and such would be dispatched prioroty 3 (no lights and sirens), and extreeme emergencies obviously would be priority 1 (pull out all the stops, do what you gotta do, if your not doing anything pressing your going clear and responding in as well) and all of the grey area calls (which there are many) are dispatched as priority 2 in which you are allowed but not required to use your lights and sirens. usually we have 2 or 3 calls pending but i know if i go 10-8 i usually ask if there are any calls pending and i'm more than happy to help out an officer on another beat if its possible. i think the system works great.