Look at it this way. What would those larger galleries look like if they had not set up the sub-categories? How would someone find anything?
IMO, sub-categories would be the way to go. I know I spent time in the old storyteller thread to see what kind of layouts had been done previously. But I had to wade through a lot of other comments without layouts to see them all. With a sub-category, I could have just gone there and viewed all layouts for any storyteller challenge.
Now, as far as the sub-categories, I say just one sub-category for each type of challenge. No need to set up a category for each month or year that it is a challenge. Because of this being a smaller community, the sub-category won’t fill up with 100’s of layouts that fast where in the larger galleries a monthly challenge could easily have up to 50 layouts just in one month.
I could see that any layouts in the ‘what you are working on this month’ threads could be posted in a member’s individual gallery since some of them are not related to challenges at all. If they are a challenge layout, then yes, they should be in the challenge gallery under the correct sub-category.
Hope you can figure out what I mean!