While I agree that perhaps the constant use of the phrase "at the end of the day" isn't such a terrible thing, I'm sure that driveupcoffee wouldn't be talking about "breaking" her boss of the habit if he hadn't agreed that he used it too much.
So maybe we can all calm down here and agree that we don't know all the ins and outs of the situation, and we can let this lie. There's no reason to continue this discussion really, is there? Driveup has the suggestions of those here who had a suggestion to make, and I think she can take it from here without any further discussion on whether or not she should be attempting to change his speaking habits.