We get a ton of time for Step 1.
8 weeks between the last 2nd year shelf exam and the first day of third year (which isn't rotations - you have a month of prep for being on the wards and then you start on the wards).
But you also have a week of spring break and then a week to study for the pharm and path shelves right before the end of 2nd year. So its sort of 10 weeks
We also host a 21 day Kaplan USMLE step 1 prep course here that is held during the time off. Different people do different things some take the course and the full time to study, some take it early and take a vacation before 3rd year.
I don't think UCI has actually their average step 1 score in a while, but I heard that a few years ago we had the highest average in California. But I've never heard an actual number.