What I had in mind is an addon which can do the following:
When a node is mined in a subzone, display a countdown timer with the name of the subzone (Can default to 20 minutes).
If a node is found within the same sub-zone, log the amount of time between timer start and mining the node.
Update default value of the the timer using a rolling average of the last X nodes found in that sub-zone.
If a node is has not been found within double the average time, consider it mined by someone else and don't use it to contribute to the average.
The idea is based on the theory that mining nodes are allocated to named sub-zones, share their own zone cap and have a relatively consistent spawn time. Ideally the addon would display a map/minimap marker for each area with the timer tagged on to it, but this is not required for testing. Theoretically this should also work for herbs excepting Black Lotus, but again not required for initial/testing purposes.