Sleeping Deeply on Saturday Nights

I have been preaching for 28 years. I am not a child prodigy, I am a Protestant mainliner who began in my twenties stepping up to the pulpit and attempting to be a faithful Gospel messenger. In my early years, I was so tentative in my speech and style that my mother, an educated and able public speaker, would suggest gently that I speak with more authority. She wasn't suggesting pulpit pounding but an inner certainty that was missing from my sermons. I worked on this. I worked for years to develop my own voice, as a writer does who has read great literature and seeks to join that flow. I listened to sermons, read sermons, wrote and re-wrote sermons. I preached from a full manuscript, preached from an outline, preached from a few key words. I made myself do children's sermons without any notes to practice standing bare handed before a congregation. My first ordained position was in a University congregation and there I had help from writers, scientists, historians and grammarians. Any advice was gratefully received. I continued to read books on preaching. I took continuing education preaching courses at the Seminary.
My interest in studying the texts and preparation for preaching has increased over the years. I delight in the study. Preparation is one of my favorite parts of each week. It's my delivery and presence in the pulpit that I'm considering here.
Now I find myself at another crossroads of preaching. I am, I think, too comfortable in the pulpit.
I read an article in the most recent Journal for Preachers (Columbia Theological Seminary in Decatur, Ga.) that no one should enter the pulpit without a sleepless Saturday night behind them. The discussion of who is upset about preaching by sleeplessness and self-doubt came up at my Preacher's Coffee Group a week or two ago. One of us said he was anxious about preaching each time he prepared. Others, myself included, said we slept fine on Saturday nights and got up Sunday mornings happy and eager to preach.
I don't know if I am picking at myself without cause over this. I am happy that I don't have to swig Pepto-Bismol every Sunday morning and beat myself up all the way home from worship then into the night with recriminations over what I said. I did that for years. But, how can I best use this comfort in front of my congregation to be a better preacher? Am I growing as a preacher or have I hit a plateau and forgotten to care about growth?
I'm thinking about this.