When you over-explain, people stop hearing your point and start hearing your nerves.

Past a certain point, extra explanation stops adding information and starts adding volume. The listener notices the anxiety in it and begins attending to that rather than to what you are saying. A confident version of the same point is usually the first two sentences and then silence. More words feel safer and land weaker.

Make your point once this week and then stop, even if the pause is uncomfortable. If they want more, they will ask, and answering a question beats filling air.