Again, I feel that's missing the point somewhat. It's an exercise in creativity more than anything, and stretching it out gives you a lot more time to think about what you're doing, whether you consciously use that time or not. That said, it is completely at your discretion how you choose to complete the challenge.
Basically, if exams are putting strain on you, then by alls means take a break if you need it, but keep in mind what the actual challenge was. I expect maybe a quarter of the people saying they're up for this to actually follow through, but if leniency encourages more people to take part, then by all means, distribute your 24 hours over another time-span.
I'm in too. I think the 24 hours split up over the course of May is a good idea. I think it would increase the quality of output.
Quality is not the goal here! It's creativity! I don't expect all that much fantastic music to come out of this.
I'll be heading out in a few hours to buy percussion instruments made of candy. My entry should be up by Monday night.