[ch00]

I would be interested to know their reasons behind this as well.

Anecdotally, it was a bad design choice for me. I took a Udacity class in the first round after their launch and followed along with the due dates pretty well. The next round when due dates were dropped, I basically dropped as well. I found myself saying "I'll catch up on this week's unit next week" until after a few weeks I was too out of sync with the course to feel compelled to keep going.

On the flip side, I felt the one week/unit deadline was tough to work with at times given work and life, etc and wished it was two weeks/unit, or perhaps Udacity to even give you an option to choose a schedule: allow a) one week/unit, b) two weeks/unit, or c) whatever, etc. This way the course still has some structure and fixed deadlines, but it's a little more tailored to your lifestyle.

[randomdata]

Choosing your own schedule seems like a great idea. I got wrapped up in more important engagements in the middle of a Udacity course and by the time I was able to return to working on it, the final exam had already been given, which kind of made me lose interest. Thrun has said in the past that AI will customize the classes the individual needs of the students, so I expect this will improve as the organization matures.