I liked random, I felt like it kept me on my toes. Sure during questions on the subject I just reviewed might have helped things stick more but I liked how random questions would allow me to review stuff I had studied in previous weeks. When I got stuff wrong or I had questions I would go back and review some material pertaining to that particular question... so I felt like I was seeing enough of other material to keep from forgetting it. Otherwise I wouldn't see cardio material for another 2 weeks until I got through everything again.
Also I didn't want to mess with the question distribution. Doing all random questions allowed me to consistently guage my progress throughout blocks of 50 questions. It was encouraging to see my scores progressively increase right up until the day of the test.
Although...I will say that you should keep an eye on your question distribution, because for some reason even doing "All subjects, unused, random", it depleted some subjects way before others. Which kind of psyched me out a little, but realistically probably didn't make a lick of difference. Still, I feel like UW should fix that glitch and have the distribution of questions per subject per test be proportional to the overall question bank subject distribution.