Yes. No. Maybe so.
Much like I mentioned in the discussion about the Protestant tag, I think the answer to this is highly dependent on the content of the question. Only experts with some experience in in the specific topic raised will be able to determine whether the question scope is reasonable. To the uninitiated any given question may seem like it has an easy answer and actually require a thesis paper to address properly, or it could seem like a broad issues but really there are only a couple of positions and a modest sized answer could break out the themes.
I don't think any formula can determine whether a question is or is not going to be too broad. Some (rare) questions may even address "all of Christianity" and be answerable on this site, while some questions about the beliefs of very small denominations might be so involved it's best to split them up or narrow the focus to a single side of a theological divide.