There is an abundance of writing advice out there, either on the Internet or from a grammar cop in the office, but it is not always the best answer. Don’t be afraid to ask the person to elaborate or do a little research yourself.
When you ask people a “how to ” question about writing, they will do their best to give you a correct answer, but the truth is, people often are guessing. They are relying on a vague recollection of what they heard in school or around the water cooler two years ago. They haven’t checked a resource book or asked an expert, so they really don’t know.
Press for an answer you are comfortable with. If it sounds too challenging to say, “Are you sure?” then you can ask, “Do you recall anyone ever explaining why this is true?” People often will acknowledge that they are not sure, that what they are telling you is what they remember hearing or what they have seen other people do.
If you have confidence in the person, then accept the answer and fix your problem so that you can finish the document, but then look up the issue to try to learn more. That way, you won’t have to look it up again and again.
The reason there are so many language disputes in companies is that no one bothers to look anything up. Companies arbitrarily make it a practice to treat certain nonwords as words or they take terms that are two words and make them one (health care) because it sounds like it should be one word or because that is the way others have spelled it.
That’s why we have great resource books and certain online sites that provide guidance. Some issues do not always fall neatly into black or white categories where the answer is almost always this way or that way. Sometimes you need to use some judgment and then be consistent. Resource books or sites can be helpful, as can English professors at a local university.