I don't agree with what you are saying; from experience, a pot of water boil over, when there is a lid on it or when the heat is very high. The wooden spoon over the pot will not keep from boiling over; may be when you put the wooden spoon over the pot, you did not put the pot lid to cover and the smoke of the pot is free to flow on the air.
The wooden spoon breaks the surface tension of the bubbles and prevents heat build up by absorbing the heat, preventing boil over. However, if the pot/pan has too much water in the first place it may be tough but if the ratio is descent it will work.
Yes, it worked for me! I am making chicken soup & I needed to bring the water that covers the chicken & vegetables to boil at med-high. I put the wood spoon on top of the pot in the middle (making chicken soup at this point does not require you to use the pot cover). There was no run over neither did I have to remove any skin foam.