It would be helpful if you could set at the resource group level if that group was time aware or not regardless of its content.
Resource group time aware ON - time slider respects date elements in metadata
Resource group time aware OFF - Layers show at all times regardless of time elements in metadata
Perhaps accompanied by a symbol to denote layer/group time awareness in orbit eg. Green/Red Clock symbol or clock / crossed out clock symbol.
Can you describe more the issue you expect to resolve? Do you have Resource Groups in which an individual resource may be missing a Set Time?
It sounds like you want a set Timeline but also want to disregard the time setting for situationally. Can you confirm if true? Can you explain a use case?