Actually, digs, the 75 word Challenge does start on the first of every month (if the theme-setter is ready...). It ends well in advance so as to give the 5 days for reading and voting and then the two days for the tie-break if needed -- and most months the last day of the tie-break is indeed, the last day of the month. So there is a basic underlying logic to it. That's not to say that other dates can't work -- the legal profession used quarter days for centuries -- but, frankly, picking the solstices for no other apparent reason than it looks exciting/cool/neat/adjective-of-choice seems, well, misguided.
My thoughts:
(1) I would not support anything which interfered with the success of the 75-word Challenge.
(2) I would not be available as a mod to do much by way of admin/organising (I leave the 75-worder to Teresa and Cul for very good reasons).
(3) We have repeatedly seen that -- with very few exceptions -- the only people who vote in the 75-worder are those who contribute a story. Moreover, not everyone who does write a story then bothers to vote. Therefore the fewer participants, the fewer votes, the less worthwhile it is as a contest.
(4) One of the great challenges of the 75-worder is to write within that specific limit. It also means that the stories are much the same length and therefore easy to weigh against one another. The higher the limit, the greater variety of length in stories and therefore the harder to make comparisons, and the less satisfactory the decision-making.
(5) We have imposed a limit of 1500 words in Critiques for the very good reason (inter alia) that work over this limit rarely gets read and commented upon. I find it hard to believe that people will read several stories of several thousand words each in order to vote in any meaningful way.
(6) Most people rattle off the stories for the 75-worder. I seem to be the only sad individual who spends days in the actual writing. This means that it encourages a greater amount of participation than is going to be found in a contest which requires several thousand words for an individual piece. The higher the word limit, the less likely it is that people will find the time or make the effort to enter.
(7) A story which is good enough to post here as an entry should be good enough to be submitted for publication. Enter a short story contest which is private, and if you don't win you can still try and tweak the story and submit it somewhere. This is an open site and therefore the chance of re-using a story is as good as lost. This will also deter some people.
(8) The 75-worder is a bit of fun which, I sincerely hope, no one takes too seriously -- but nonetheless receiving no votes and few or no honourable mentions for something of which you are proud can be distressing. Writing a long story which might take a considerable amount of time and effort will involve a greater degree of emotional investment -- and therefore a greater degree of emotion if the story receives no votes, and consequently a greater risk of upset within AW.
(9) I'm not an expert, but the short story contests I've seen require anonymity so that people who vote, do vote for the story, not for the person. That ain't gonna happen here -- so again the decision-making is not as good as it should be. With the 75-worder, and a monthly contest, that isn't a problem. Elsewhere it might be.
Finally, cheating. Sorry to raise this ugly head, but if there's an elephant in the room, I like to talk about it. We have a rule in the 75-worder that one cannot vote for oneself. We have no way of knowing whether anyone does. I hope not. But with the great number of participants one vote only makes a difference if the story has already picked up several votes and therefore is, in a sense, a worthy winner. (No winner has received fewer than 5 votes.) With fewer participants, and therefore fewer voters, there must be a real risk of several stories having, say, two votes, and therefore that "cheating" one would be decisive. This -- to my mind -- is another reason to want to increase participation, which -- again to my mind -- means bringing the word limit down.
Sorry to have wittered on at such length. The points I've made are none of them insuperable, but collectively they push me to think that a challenge of this kind isn't something which should be rushed. Having said, that we were greatly surprised by the enthusiasm for the 75-worder -- we originally only expected about 20 or so entries each month -- and some of the concerns we had proved unjustified.