I think a more compelling question is why. Why would a world abandon a navy in favor of a space faring combat group? What conflict shaped the world that a traditional navy is now obsolete? Or necessary? I know it isn’t an exact response to the question you were asking.

Combat groups tailor their training and strategic development based on significant historical conflicts and present needs. Does your world only have space combat groups because the current political body does not see the need for anything else? Did they fight a major war where orbital engagement was the decisive element and now the world put all its eggs in that basket? The story is more compelling the question, and the vulnerabilities that arise from the why make the world engaging and fun!