Does the number of knocks on the door differ if the homeowner is expecting a visitor?

Question:
May Allah reward you, Honorable Shaykh. These are many questions; I am presenting to your eminence whatever of them is feasible. This questioner says: If I have an appointment with my friend, is it permissible for me to knock on the door more than three times, or to ask for permission more than three times?

Answer:
No, the evidence indicates that one does not add to three, absolutely. If he is ready, he will answer from the first time. Yes.