Paul was the apostle to the Gentiles. It was his province, his area of authority, his area of influence. Paul says that he lived within it and worked within it. He did not go into other men's areas to extend his influence beyond what was given to him. Peter was made preeminent over them all, and then as the work grew, God divided it up, saying in effect, "Paul, concentrate on this. Peter, concentrate on that." They had leadership in those areas, and it was almost as though the two shall never meet.
The picture that appears from all of this is that, not only did Paul adhere to the sphere of influence that God had given him, but so did the other twelve apostles. They divided up the world, went to their areas, and conducted their spiritual and governmental responsibilities only within their regions. That is the only way God could keep order over a worldwide work at the time.
The people who responded to the teaching of those men in those areas were not confused by other voices speaking to them. Each stayed within his own sphere of influence, the one that had been given by God. In that area, he was the top authority, as far as the doctrines that were to be followed, and in this way, God could keep order. Quite likely, the apostles were all speaking the same thing, yet by this method, confusion in terms of government was kept to a minimum. The people were not confused about whom they were to look to in their region for authority in matters pertaining to their relationship with God. It is a wonderful system.
God is not the author of confusion (I Corinthians 14:33). Doctrine was put into the church as the work expanded in the way that He has always done it - as He did through Moses, through whom He gave the first five books; as He did through Samuel, who may very well have been the author or main editor of all the books from Joshua to II Samuel; then through others whom God used to add to the scriptures so that we might have the complete Bible today.
So, it is God who puts doctrine into His church by the man He chooses to be His ambassador, His representative to those who have been called. That keeps matters in order. Our job is to have faith in God's decision and in the pattern that He reveals in His Word. That will keep us on track if we choose to make the right choices.