Been in L.A. since 1972 - I use my turn-indicator/blinker/turn signal (whatever anyone wants to call it) ALL THE TIME.
But to Freerideany1 's point. L.A. has some of the more polite and gracious drivers (I've driven all around the world and country) BUT do not ask to get in front of L.A. drivers in THEIR lane! lol
Little old grandmas will speed up like they are in the Indy 500 to keep you from getting in front of them!
That said, time the blinker just right and they don't have a choice but to let you in, while not feeling disrespected. Also, I always give a 'thank you' wave once I am in the lane safely. Works like a charm 99.9% of the time - just watch out for Grandma!
Weekend drivers suck but rush hour in the core the drivers are the most forgiving and accommodating I've ever experienced. It's pretty much just taxi's and other Ubers honking and fighting for position.