https://docs.inductiveautomation.com/display/DOC81/Tag+Groups
"Note: Viewing the Tag only in the Tag Browser will not cause the Tag Group to execute at the Leased Rate."
https://docs.inductiveautomation.com/display/DOC81/Leased+Tag+Group+Example
"Let's add a new Leased Tag Group that polls a Tag from the PLC at a 1 second rate when someone needs to view that Tag in the Client. If the Client is closed, or the Tags are not displayed in the Tag Browser of the Designer, the Tags will not poll at all."
The second quote implies that if the tags in the leased tag group are displayed in the Tag Browser of the Designer, they will poll at the leased rate, but the first quote specifically says that does not happen.