*I* personally wouldn't drink coffee that's been brewed the day after you make it
but maybe Sbux just has me snobby, lol. If you're not using espresso, I would at the VERY least make just regular iced coffee which involves brewing coffee double strength. At Sbux when we make iced coffee we brew a full batch (measure) of grounds on a half batch setting, and then ice it while it's still hot. (and then add ice again when we serve it) I realize we have super-high freshness standards, but we throw out iced coffee after 8hrs (refrigerated).