From the docs, URL https://www.novell.com/documentation/idm36/idm_common_driver/data/bdyim5q.html , seems like the driver health Job can only be associated with a single server at a time. This is my impression from the sentence "Servers: If the driver set is associated with only one server, that server is selected and cannot be changed. If the driver set is associated with multiple servers, select the server where you want to run the job."
Yes, the job can only run on one server. It will, however, monitor the drivers on ALL the servers associated with the driver set.