But it reminds me that while not everyone will like one’s advertising, even the most forgetful people in the world, such as me, will start to get fed up if the same advert appears over and over again.

Which is why it is always a good idea to change one’s advertising as often as one changes one’s socks.  Sending out the same advert over and over is a bit like the person who always plays the same shot at tennis.  It might get the odd point, but after a while the opponent not only learns how to deal with it, but also gets rather bored and goes off to play with someone else.