Don' leave it until very late to get your extension as it is added to your permitted to stay date and you don't want to go too close to the New Year holiday unless it's with an appointment then you have to hope you got everything 100% correct
That is a local notice put up to say what the local rules will be. There are countless posts on here of people recently entering for the 5th, 6th or more times this year, clearly rule 1 is not a national policy.