If the task is a long running expensive task, it's going to block the main thread from being responsive to user input. If it's a quick task then you don't need

If the task is a long running expensive task, it's going to block the main thread from being responsive to user input. If it's a quick task then you don't need to schedule it. I struggle to see the place for a medium length task which is long enough that it needs to be deferred but short enough that it can't be executed immediately. What would be an example?