Between 8 and 12

If anyone has every had cable installed or something repaired in their house has heard the following: "We will be there between 8 and 12." or "We will be there between 12 and 5." You would think they could narrow the time down a little more than that. I recently had my AC serviced. The company doing the work said, "We will be there between 8 and 12." Well, they made it within that time. The service guy arrived at my house at 11:56 AM. Four minutes to spare! What's next? We may show up sometime this week.