I've always wondered about this as well...just how "intelligent" are Wizarding pictures anyway? For example, in the Headmaster's office, Dumbledore (or was it one of the former Heads?) once said that the past Heads portraits are "honor-bound" to give assistance to the present Head. Just how much assistance could they give though? So far we've seen them comment on the goings-on in the office, but not so much big help. We dd see Phinneas going back and forth from the Office to Grimmauld Place to bring messages. But so far, none of the portraits have really given any wise advice or anything.