The description of group-timeout attribute in CLI says:
How long a group binding will be used, -1 means for ever. Bindings are removed after this wait elapses (only valid for LOCAL handlers).
However the attribute is valid for both LOCAL and REMOTE handler. If you configure the attribute with REMOTE handler it specifies how often the REMOTE will notify the LOCAL that the route (group binding) was used.
The Artemis documentation  also suggests to configure the group-timeout for REMOTE handlers.
In case you are using group-timeouts, the remote node should have a smaller group-timeout with at least half of the value on the main coordinator. This is because this will determine how often the last-time-use value should be updated with a round trip for a request to the group between the nodes.
JBEAP-4406 Incorrect description of group-handler/group-timeout attribute in CLI