Traffic is such a funny thing in the LA area. (Definitely not "haha" funny!) It's constant, and there are so many areas with construction that you have stop and go traffic even late at night sometimes. So I totally get MillauFr's response!!
But IMO, if you are stuck with a daytime drive, I'd say aim for 10-1, 1-2 is dicey. A few weeks ago, we started to head down about 1:30 from Westwood, which was (based on my research) not quite ideal but not horrible. It was looking to be 1h15m or so. Then we had to make a 20min stop... and I watched the drive time shoot up and up. It was about 2h in the end. Using HOV isn't a help in the same way it is in other cities.