Seems like it'd get unwieldy fast. Would need an efficient interface for listing and editing registered tasks, or you might get stuck with a couple of hundred tasks of the type 'Alexa, say fart fart fart at three/four/five in the morning' if a kid ever where to pass through the house.
We're not asking to construct a complex schedule via voice command, the app is sufficient for that. Sometimes you just want your curtains opened at 6:45 tomorrow because something is happening and you just thought of it. That's would actually be convenient.