From ScoobyNews.com:

At 3 miles, Buttonwillow is the longest and most technical track in the Los Angeles area. With twenty-three turns, three elevation changes, the banked “Riverside” sweeper, and a perfect drift over “Lost Hill” (AKA “Magic Mountain”), Buttonwillow offers both a unique learning environment, and a challenge to advanced drivers.

Track configs will be 13A CCW (”A” denotes the new turn as depected below, replacing buttonhook/offramp) Saturday and 13 CW Sunday. This track is suitable for street cars, though we suggest that the Riverside turn should be approached at conservative speeds of 70-80 mph in cars without race rollover protection. The remainder of the turns on this track are moderate-speed (35 - 70mph). Most Turns have wide runoff areas, clear of major obstacles.

The typical schedule is three run groups, with five sessions per group, 25-30 minutes per session, though they do occasionally go to a four run group schedule when conditions require it.
More info at the website