> In many universities, major programs for CPSC, physics, etc. require courses with prerequisite chains that take several years to go through.

At my university, UCSC, math and CS courses tended to be "structured" in the opposite way -- once you'd completed a modest suite of lower-division courses, you tended to be qualified for almost every upper-division course. I assume this was meant to make it easier for people to graduate on time.

The considerable downside was that nearly every class devoted a substantial percentage of the total time to review at the beginning.