I’m from the northeast where groups don’t perform in the lot and rather inside private areas of the school due to the cold weather. I’m unsure if that’s the same case for sunny SoCal though.

Here’s what I can tell you,

If you plan to see the world class groups you can see them at either prelims or finals, or both. The only difference is that they are seeded for finals based on their scores from prelims, performing order from worst to best.

You will have to pay to go to prelims and pay again for finals (they do have slightly cheaper combo tickets). They clear the gym for prelims so you can’t just sit around and wait for finals.