We may want to establish a system that determines this for us.
We could have one protocol that counts the number of entries per week or another that checks for a threshold in total entries, perhaps something that implements several indicators, since interest is also a contributing factor(Hey, this could be a challenge! A meta challenge!)
But one good thing about these challenges is that I personally never really perceived them to have a time limit. I completed Ultimate Tic Tac Toe due to the community challenge but I hadn't even begun using the site till a year after it was posted.
A challenge is ideally: interesting, feasible for those interested, have nuance that makes it actually challenging, and also depth that make several entries personal.
The biggest reason I find to increase or decrease the frequency of these challenges is probably just the time to choose them in the first place. Some things are very field-specific and not a good choice for an entire community.
I see merit in challenges that can be simple to start, but optionally have depth.
Learn a new language.
Is it interesting, widely feasible, personal and challenging?
- Anyone curious about X language, just got an excuse to delve inwards.
- Tons of tutorials available for most languages.
- Challenge inherent in learning something new.
- Different languages learned and no specific end-result means it's definitely personal.
Implement X - x being something general like a 'game' (there's a reason these are popular).
User will definitely pick a method that is feasible, yet challenging enough to be worth writing, of course it'll be something interesting to them, and all entries would inherently be personal.
Again, anything simple with a variety of optional improvements is good.
- Simplicity means more contributions.
- Optional depth means they will be personalized and relatively challenging.
Then the only task we'd worry about is making sure it's something of interest -- of course there's no requirement to fulfill all the points, but I'd say that lately some of these propositions have assumed interest by virtue of being a community challenge, which definitely isn't the case when they become monthly.