dmd docs
Are the offline maps updated regularly?
Yes, new map builds are published regularly. There is no automatic map update in DMD2, on purpose — an update that ran by itself could leave you without navigation part-way through a ride.
You are told about updates instead. The Map Configuration button on the map view shows the number of available updates, and each map carries an update badge.
To apply them, go to Map Settings → Offline Maps. Use Update All to refresh everything in one go, or open a region and update maps individually.
A data connection is required. Once an update has started, the map being updated is not available until it completes — so do this before you set off, not at a fuel stop halfway through.
Updating a map you already have does not count against the free tier's three-map limit.