(Currently) they’re updated every 24 hours. This frequency is configurable. There is a pretty aggressive trade off between player bandwidth and resource map accuracy.
We have also explored options for making them realtime for your local environment. But decided we would release this version to help players today, and then review if we wanted to the do the additional work to make them update in realtime later.
The dense resource maps (copper, iron, coal, etc) feel like they don’t need to be realtime, but the sparser resource maps could more easily be out-of-date.