The LASD patrols the unincorporated areas of LA county, and has several “contract cities” where they also patrol.
As you point out, the SO also staffs the county jail.
When a new deputy graduates from the academy, he or she is sent to the custody department for a couple of years before being sent to a patrol station for field training.
I wonder how they mutual aid during this type of stuff. Sometimes when you’re there, hard to tell if you’re in the county or the city. But those who work it every day know the boundaries and some of contract cities are easy to figure out.
Best wishes. Glad i’m not there.,