It depends on the Network and “type” of reality show. Different Networks have diff rules on how much “scripting” / “dramatization” that producers can do. As a matter of fact, it’s written into the insurance that a Network takes out on a program. “Documentary” versus “Competition Reality” versus “Scripted Reality,” etc.
On a show like “Little People, Big World” producers are more likely to film a LOT of footage for an episode and cut down the story from there than to create fake scenes. They’ll shoot weeks even for one storyline. They may help that storyline along by asking leading questions, lining up new interviewees, etc. But these people are not paid actors.
On a series such as “Family Jewels” you have real people (as real as celebrity families can get, just remember that no one is likely to be a paid actor who auditioned for the part) in semi-real situations. Some of these situations – say, a school dance or doctors office – are true. Characters will be going through this at that time but it’s scheduled / scripted: “Ok, let’s go dress shopping! what if dad doesn’t like the dress? What if the date doesn’t show?”
So it’s pretty across the board, I could go on with more examples but you get the idea.