There is no period of my gaming life when I used a GM screen. They were always in my way while we were playing. The only time I did use one – I used it as a mouse-pad.
My eyesight is going bad, and is forcing me from my love of paper books to digital. A lot of the publisher use font so small, or with low contrast that I can’t read them. So I started investing in decent tablets with superb screens. The ability to zoom into the text is a big quality of life change for me.