I think there has been a PR in the past that added validation but it didn't make it in. Now might be the time to bring that back?

I'm not entirely sure where that throttled warning should go. I'd rather not stick it in here as this will get called on close to every page load (multiple times) and already does checks for a negative duration. OTOH, it seems a bit much to add a `Config.on` method for something that should go away with validation?