I think the one month time limit works fine, as said before if there's many people who are working on something when the deadline's up we can just add two weeks extra. There's also no reason why you can't continue on a project when the challenge's over, the whole idea is to get started on something you might not do otherwise.
If someone would rather have their thread moved over to WIP than previous challenges just give me or Jay a shout. In real life you have to work to deadlines and sometimes you might have to hand over work you're not 100 percent pleased with and let's face it there's almost always room for improvement on anything.
For friendly reminders we can all remind each other by commenting on people's work, this also bumps challenge threads up on the front page and into new posts. There's simply no space on the front page without making it look like a cluster f***, unless we take away WIP threads or resources which is more important for the site. We can however add a challenge sticky to the basics lounge (which is still getting all the traffic at the expense of other lounges
) to bring some more attention to this one.