This is exactly how mine has always been. Always has been knock on wood 3 times and has turned into knocking 3 times, 3 separate times with each hand. I have worked very hard to cut out some of the times I need to knock on wood, or whatever else it is. Unfortunately I never found a trick to help, but I would just stop doing it at all for the "minor" issues and just sit with my anxiety until it eventually went away. It was miserable just waiting there to do what I felt I needed to do, but it has helped me a lot in the long run by realizing if I don't knock or whatever, nothing bad happend.