Does it matter if two cooperative houses use a six-story and five-story gable?

If the gable you are talking about is T-shaped, or it is on the back, it doesn't matter if the two houses are used together. Because each has its own portal, good or bad depends on each family. If you have neighbors, you can't be higher than your home; On the left is your green dragon position and on the right is your white tiger position. If there are only two, that's not the case.