Applying unavailability filter on all or multiple resources

I have now searched through all functions at the back-end, but I can’t seem to find an option to set an unavailability filter on all or multiple resources in one go. Is there such a feature? I would like to block out all resources on e.g. for an entire month when all resources are closed for refurbishing without having to go through every single one of them every single time.

No, there’s no such feature.
Regards