Are Ambulance Response Times to Slow?

Having worked in EMS, I know first hand that no matter how efficient an EMS system is, there are times when it will be pushed to the limit and people will have to wait for an ambulance to arrive. The question is: What is the standard? How often should an EMS system (or any public safety agency) be allowed to delay response times? Below is a video that discusses Philadelphia's EMS system and how it is regularly being pushed to the limit. Is this fair to the public for which we are there for?

Medevac Helicopters Crash in Flagstaff, Arizona

Having worked as a paramedic, this crash really makes me sad. There has been alot of talk (maybe not enough) regarding medevac helicopters being needed for civilian purposes. This is similar to the question of using lights and sirens on every call or using priority dispatching. Or using a courtesy blue light on a volunteer EMT/firefighter's personal vehicle. Or police cars being involved in high speed chases. Is it worth taking the risk? Is if fair that innocent paramedics/pilots/nurses be killed when there is a possibility that a medevac helicopter isnt scientifically proven to save lives?

Here is an article that discusses the dangers of using medevac while also mentioning that there is nothing proving that time is saved:
Medical Copters Have High Crash Rate; Some also say travel time isn't significantly less than ambulances


Click here for complete NY Times Article of the Medevac Crash