@Douglas: " but it might be better to sample a class in the middle of the previous term" -- that's actually what I meant. I'll update the post to clarify. At UChicago, classes generally get full before the quarter begins, so it's hard to make changes even if one wants to, after the quarter begins. So people who don't sample classes the previous quarter are often stuck.

Also, thanks for sharing your thoughts! I really appreciate it.