I think all those theories are utter nonsense.
I evolve in my writing style, emphases etc. from one year to the next--certainly over 10 years or so.
Paul was not frozen in time. He grew in the Lord and in his wisdom in The Lord! God is good about that.
Those of the "higher" textual criticism schools are usually some of the worst idiots in theological circles, imho.
Amen. They construct straw houses in dry and windy weather.