After decades of driving I just had a thought that maybe I was adjusting my side mirrors to look too much towards the car. I had instinctively been setting them so my view is "straight backwards" and I see the door handles of my car in each mirror. Realizing that a few times I was caught off guard by someone in my "blind spot" that I couldn't see with my mirrors, but could see when I turned my head very far around, I thought I would try pointing the side mirrors outwards a bit more. I don't really need to see all the way back in the distance, and I think a smaller blind spot would be a good tradeoff. After driving this way for a few days I got used to it and think it is an improvement. (Never too old to learn something new I hope).
Today I checked and lo and behold I see that some sites recommend this very change in habit:
How to Set Rearview Mirrors to Eliminate Blind Spots - wikiHow
Adjusting Your Mirrors Correctly - Smart Motorist