This is why I am doing it with 35mm and street shots. The faster you get ready the better. Sometimes I see something and I pick my camera and just before or after I shoot I realise I forgot the put my glasses on. Even worst when I forget my glasses at home. But even with glasses, you you know when you are trying to focus on something moving towards you. The faster it moves the less precise or sure you are about the focus. But when you look ate the space without look through the viewfinder and see where the moving object is going to be and you want to shoot, you just see the distance and use it as reference. Much faster than trying to focus the area before the moving object rich there and your have to shot to get what you want.
With wide lenses even easier to get it near spot on and everything in frame without looking into de camera. But I still have to wait to see the results.