I only ever do maximum a few hours notice, I never plan punts in advance. I agree though. I've had some listed Avaliable Today but when I messaged early they said they aren't working today, or only working from some time much later in the evening.
I'm not 100% sure (maybe SP can correct me) but I remember seeing somewhere you have to pay to mark yourself available today, and I know for a fact some SP's are listed AT despite not having logged in for several days so I'm guessing maybe AW let you buy a whole week AT for discount and they still leave it up even when they aren't working.