We should get sitemaps quickly and keep up with their changes. This is especially true of our own.
Paul has already written the server-side support for most of this improvement. github 
How many sitemaps are too many? If we get them fast will we want even more? Hundreds? Thousands?
We could prune the neighborhood to only those sitemaps called for by the current lineup. This would mean that the lineup url will accurately represent a neighborhood. See URLs not Idempotent