‘You should have thought twice before you went to the boss with a private matter.’ / ‘You should clean your car more often.’
These are assertions whose objective is to indicate that there is only one right way of doing things. Instructions usually push the other side into defensive mode – they may try to prove their point or they may remain silent on the matter. In both cases there is no free flow of information, because the conversation aims to show who is right. Effective communication is not about being right, but about both sides expressing their views and developing mutual understanding. In the case of instructions, both these components disappear.