Everything legal in the LA Basin was over by 10:30 at the latest, unless there was a football or baseball game involved. I know, because I used to be involved at Devonshire Downs every year for decades.
They had to pull out the ones that didn't go in the show, tie on more fuse and get them shot off before the show permit expired at Midnight - Couldn't take them back without getting another Hazmat Trucking Permit for one or two shells, so it all had to blow up. I got handed a lit flare a few times and told "Range clear, here you go - watch your head..."
And once they handed me a fresh flare as a test - but I've stopped at a lot of accidents and popped a Lot of flares, so that one was easy to pass with style.
They keep running PSA Messages on Every TV Channel and every radio station: "You shoot it up in the air, we arrest you! Don't do it!!"
You can see just how much actual enforcement the local Police and Sheriff's do by the amount of professional grade aerial mortar shells being employed. I was seeing people shooting off 4" 6" 8" and 10" shells (with tails and everything) from residential backyards. The Tails work both ways like Tracers, but they don't care - it's almost a "Here's exactly where it came from, I dare ya!"
There are several 1 second per minute time-lapses up online, it's astonishing, and from all over.