They don't run them all day. Perhaps I'm misremembering, but I thought the things that got reported the most were "unofficial stat lines" of offense vs defense type drills and really egregious mistakes like the infamous hospitality tent. Some players got commented on for tons of drops, or interceptions, and/or bad days in general.
That's what I remember from last year anyway.
At the end of the day, it's just practice. Remember last year the defense had to be held back because the offense sucked so bad? And then the offense was clearly the superior unit? No big deal if that info gets out there IMO.