This is inspired by cases where a bunch of items is not necessary and therefore disabled but get now and then enabled when needed for analyses. The drawback is that those items might get forgotten to be disabled again after a reasonable time - and might produce a lot of unnecessary history data and load.
With hundreds of hosts this might be manually maintained but taking care that thousands of hosts collect only what is desired will be a real pain.
What I think about (and it's actually not thought to the end) is something like an optional TTL for items, trigger and maybe even actions and hosts.
If set it may be indicated in frontend by a symbol like it is already done for maintenance periods or no more discovered items.
If the time is up the item, trigger, etc. gets disabled. Disabling might also create an event that can be referenced in action conditions.
The TTL should support User parameter to allow for example predefined values in templates be overwritten on host level.