Patrol officers shouldn't all be SWAT. That's a specialist designation that should be reserved for extreme cases.
When everyone is outfitted and trained as a militarized unit, they treat more situations like a military exercise. When someone has a warrant because they forgot to pay a speeding ticket, they shouldn't be breeching doors. When someone threatens to kill themselves, they shouldn't respond with armored vehicles and sniper rifles.
That's what the militarization of beat cops has done. They're trained and equipped in a manner that causes them to take extreme measures that do not serve the needs of the public. Essentially, every police call is now an activation of SWAT, which is overkill 99.99% of the time.
We've actually needed a militarized response zero times in the history of our department, but they devote massive amounts of resources to the ability. Those resources would be better spent on fire prevention, infrastructure maintenance, and municipal projects while relying on our already-existing mutual aid interlocal agreements for heavy police response in the event it's ever needed.
As for timing, right now if there were an emergency, our police would travel to go to a scene, gear up behind the cars, and make plans for a response, then engage. A SWAT team from a nearby agency would gear up and make plans while en route in the back of the van and be ready to engage just as quickly while being better trained for the job.