Innit. Plus most people probably won't have cash there and then. All he needs to do is drop the card with the papers one day this week and then between now and Xmas he will get a load of cards stuck to the door hopefully with some cash. No awkwardness. Nice faceless transaction.
Door knocking definitely too brash, suspect it may put some off. Drop a cheap card in with their papers over the next few days and then count the dough as it comes rolling in over the next couple of weeks.