I think your first theory worked better for me. The hogs here sometimes appear just after the food has been put out, too, but possibly more often if there has been a refill.
I still have the one mature female visiting. Am slightly worried that she is looking slightly sleeker, and hope she hasn’t had hoglets this late. The two ‘regular’, now large, hoglets are still visiting as well. (I always half hope that they will hibernate before the clocks change.) This time last year there were loads of small hoglets around into the beginning of December. This year I haven’t seen any new ones since this lot, who first appeared in July. A friend, sadly, found a small dead hoglet, recently (no obvious reason). I suppose the only consolation is that it shows the hogs there were breeding and just hope one of it’s litter mates survived.
Good move, getting some posters out, especially with bonfire night approaching. Last year Penny did a brilliant one. I’m sure I must have saved it somewhere, but can’t find it at the moment. I think posters are always worth it, even if, as you say, it only saves one hog who wouldn’t have been saved otherwise.