I really don't think a cooldown period is all that necessary, honestly.
My ideal system would be SM63-LL alternating every month, a contest officially starts on the 1st and ends on the 30th- even in the case of non-leap-year February that leaves 28 days, with six of each contest per year. I think if you can't finish a level in a month, the idea is way too ambitious for a contest. Following this, judging would extend 15 days into the next month, so even if some judges were competing in the next LDC, they'd still have half a month to put something together. Seems more than reasonable, assuming they don't attempt a 16-part story entry with fully programmable block boss at the end of each installment, right? The judges should ideally be able to wrap things up in half the time it takes people to make entries, too. It's a commitment, and one that comes with time restrictions. I remember
doing the math for the 25quared contest back in April and estimating about 10 hours of of work per judge- yes the levels were small, but there was a lot of them. At an hour a day, that's about ten days. Not really seeing an excuse here, barring something crazy coming up.
So yeah. This gives clearly defined start times and deadlines, and while they are perhaps a little on the short side, I think they're a pretty reasonable compromise between spending ages on a perfectly polished level and dragging the contest out so long nobody cares when the results eventually come out. That's where a lot of the hype (and stress) comes from, and anyone who's ventured through the latest contest threads can see the huge number of people beating themselves up while waiting for things to conclude. It's pretty morbid. Not many of our users do LL and SM63 super regularly, so the duration of one contest would be like downtime for the other guys, and even if you want to enter both, it's more than possible to do so by not procrastinating your entry.
If judges are that hard to find, I could judge both games pretty much whenever. Bottom line though, I think we need to handle the next few LDCs with a "tough love" approach. Sometimes things happen. It's not the end of the world if you have to sit out one contest, but proper time management could greatly reduce the impact of things like computer crashes and deleted code. (That and saving your work, USB drives are very cheap these days and are almost universally compatible between operating systems, home computers, laptops, and school/work/library/whatever setups.)