I work core seven days a week.

And I fully advocate for it if your goal is a powerful core that can do what it's meant to do - protect and stabilize your spine.

Now, that isn't to say that I'm doing hardcore ab and core workouts every day regardless of what I've already done. Included in that seven days is, of course, the fact that we're all doing indirect core work all the time. There isn't a single strength routine you'll do that isn't activating the core to some extent. However, I do throw in direct core work whenever I can.

The core as a whole, not just the abdominal muscles, are a heavy volume set of muscles. Lots and lots of type 1 muscle fibers. Heavy load, not fast twitch. Takes a lot of work to train them up because they're used to doing a lot of work. Anatomically speaking the abs themselves, the part people worry about being visual, are very thin. They are not prone to hypertrophy and intense growth, meaning that working them and getting them nice and strong is not going to lead to weirdly extended or distended abs. In the case of distended barrel bellies you see on some bodybuilders, that's caused by a lot of things including terrible form.

Regardless of if you do it every day or not, train your core often. It will help you with everything else you do, and help keep you healthy and your spine happy.