Who would want to pay to be #8 of 14 in a row?
Who would want to be an artist whose song is the third in a set? Same thing. People tune in and tune out of stations during an hour. They don't tune in at the top of an hour. It's possible they will tune in during spot #8. At that point, your spots is the first they'll hear. It's all relative.
This argument about being the 8th spot out of 14 is completely irrelevant to the people who care, which are the advertisers. They have the exact same situation in the placement of their ads on TV. The spot sets aren't any shorter in TV, and around this time of year, you'll likely see multiple car spots back to back. Things will get even worse in December. Advertisers understand the context of their spots. They could pay more for fewer spots, they can buy the first spot in a cluster, or they could sponsor complete hours where they're the only advertiser. Those options are always on the table, and the advertisers prefer to buy what you're hearing. These advertisers are buying hundreds of spots. Sometimes they're the 8th spot, sometimes they're the 1st. They're buying frequency and impressions, and they don't care about placement. If they did, that's what you'd hear.