www.sb-court.org
The court's normal hours of operation are
8:00 AM to 5:00 PM. Prospective jurors should make arrangements to remain the entire day.
This is for San Bernardino but I suspect it's very similar across the state of California.
ETA: This is what I found on the San Luis Obispo court website
www.slo.courts.ca.gov
Normally, service may be required as often as once per year. Service lasts from one day to the length of the trial, starting at 8:00am and ending at 5:00pm.
I can't find anything specific to deliberations.