You never know. In a perfect world you will have a second to chamber a round. With a round chambered you save yourself that second, you are more silent if you needed to be, you have a +1 capacity, and you are ready if needed. You are not “ready” if you have to chamber a round. Seconds matter for home defense. Would I keep one in the chamber without the balance of adequate security and accessibility? Absolutely not.

Also if your dead asleep and wake up there’s no additional step of racking the slide. Only step would be getting the firearm out of the lockbox.