Not so much for sweat, but I go through at least two shirts daily - one for day, one for night.
I say at least, as I do have other reasons to change. I'll change to something more expendable when I'm cooking something that may splatter. My mood may dictate a change on some days/evenings too. And if I wear a Ramy shirt around my dog, it's essentially guaranteed that she will drool and/or leave her slobber on it.