<p>Are the times for the same class different from year to year (especially the popular ones)? Or do they differ greatly?</p>
<p>The ones that need the very few rooms that house 600+ sized lectures are likely to be at similar times for lecture, Chem 1A for example, but in general the answer is no, other than coincidentally. The lower division classes more likely to fill the morning slots, especially 8AM.</p>
<p>Apparently, it has long been tradition that Biology 1A/1B lectures are at MWF 8-9, and organic chemistry lectures are at TuTh 8-9:30. Pre-meds get these lectures done early, leaving the rest of the day open for labs.</p>