Why do we need moral consistency

Moral consistency requires that once we make a set of moral, that we should keep to them, and not change them willy nilly.

Explanation: Lets say that the first set of morals said that you should not lie. However, some people decide that they want a different set of morals, and try to change the overall set of morals. This will confuse others, making it hard to maintain a set of morals. (Hoped this made sense)