On most days I give very little thought to how my actions affect those outside of my house. I go through life thinking I am a good person, and I hope to get to Heaven someday.
King David thought that, too. He was the anointed of God. What could possibly go wrong? The prophet, Nathan, was sent to tell King David things like, "God does not require a house," or "Taking someone else's wife has consequences."
I believe I would benefit from a Nathan in my life. He could tell me things like, "Sloth is one of the many paths to Hell. Just saying..." or "Thou shalt prepare fresh produce for thine offspring." Whichever message he feels would get through on a given day.
On other days I am prone to scrupulosity. Having a Nathan in my life would help with that, too. "Relax, you're doing fine," or "Thou shalt allow the Lord God to move in thy life and offer the Lord God your faith in His plan."
Having a shoulder prophet would also eliminate the debate between the shoulder angel and the shoulder devil. The shoulder prophet could cast the deciding vote. Angel and Prophet always agree, and the lies of the devil are always exposed.
On hearing this, David flew into a rage against that man, and he said the Nathan: "As the Lord lives, the man who has done this deserves to die. He must make fourfold restitution for the lamb, because he has done this without showing the least bit of pity."
Then Nathan said to David: "You are that man!" 2 Sam 12: 5-7