I read that Vilna Gaon emphasized the need to read the Shema from the Siddur rather than to say it by heart. This from a man who had a photographic memory of Gemara. I assume the reason he insisted on this is the chance that we could unintentionally leave out or misremember passages we have been saying since we were small.
I get the point about closing your eyes while saying Ashrei, etc. I find myself doing this at Shacharit and Mincha.