You must drive much faster than I. Also, when I say "in reality," I'm assuming the average person will need to stop for gas and/or food in the span of 6-7 hours and I've never been on a freeway in or around LA when I didn't spend a length of time below 25 mph and/or stopped - so I included that assumption as well.
If you have to drive thru LA, i would definitely agree. However, to get to Pasadena, that isn't necessary. I lived in Citrus Heights for a while and made that drive many times.
Oh, and i have a large bladder.