I put shift in an out-the-way location because I have this setting in which I can hold down a key for slightly longer than normal to get the shifted version, and I mapped a key to do ctrl-shift-c/x/v, depending on how many times it tap it. So, I haven't needed a lone shift.
I was just editing a Google Doc, though, and there's no way to select a lot of text via marking sections with the keyboard. I have to either shift-click on hold shift while I PgUp/PgDn. I guess I can see why people have layers for specific tasks, but again, that seems way too confusing.