San Diego will staff 6 "peak hour" engines

https://web.archive.org/save/http://www.latimes.com/local/lanow/la-me-ln-sd-fire-response-times-20171230-story.html

4 man crews - 9 AM to 9 PM

response time goal is 90% of all calls in 7.5 minutes - which roughly translates to an average of 4 minutes I think