We've had a number of questions on this site of the form "Here's a picture with dozens of characters/items from sci-fi and fantasy - can you identify them all?" Such questions have generally been welcomed by the community as a chance for everyone to work together and have fun.
In that spirit of working together, what often happens is that a single massive Community Wiki answer emerges where many users make small contributions, sometimes amounting to hundreds of edits before everything is correctly identified. If there were other non-CW answers posted, the answerers sometimes self-delete those in favour of cooperating on the big CW answer.
It's not always the case that a CW answer is posted - e.g. here and here a single user did most of the legwork and retained ownership of their post - but in some cases, after a CW answer rises to the top, there's been debate in comments over whether or not others should delete their answers.
Today I just realised that there is a mod tool available to restrict the thread to one CW answer!
If it's what the community wants, we could use this in certain circumstances, on certain posts, to restrict people to editing an existing CW answer instead of posting a new one. But first we need some community consensus on how, when - and indeed if - this should be done.
EDIT: the "wiki lock" for questions doesn't work as I'd thought. If we don't want to prevent the question from being voted on, then this isn't an option. I'm slightly re-scoping this meta: feel free to discuss the possibility of forcibly CW-ifying answers as well as wiki-locking questions.
Should we begin forcing CW answers to some/any mass-ID questions? If so, which ones?