For years I was glued to my dials and readouts. Then I tried just watching the metal change color, and it was a game changer. My guesses got better, and I stopped second guessing myself. It turns out my eyes are better than any gauge I ever bought. Now I look back and wonder why I made it so hard.
Actually, it's not about tools being bad. They give you a number when your eyes see a shade. My old mentor could tell the temp within 25 degrees just by the color in a dim shop. But he still checked with a pyrometer on critical welds. The tools back up what you see, they don't replace it. You need both.