Final answer:
Commercial-free music blocks limit advertising opportunities, as no ads can run during these periods, and subsequent ad clusters may be skipped or ignored by listeners, reducing ad campaign effectiveness.
Step-by-step explanation:
“Commercial-free” blocks of music are a disadvantage for advertisers because they are followed by long segments of commercials that listeners can easily skip. During these uninterrupted stretches of music, there is no opportunity for advertisers to air their commercials, which means their potential to reach listeners is limited. Moreover, after a long block of music without interruptions, there might be a concentrated cluster of ads, which listeners may avoid by changing stations or tuning out momentarily. This significantly reduces the effectiveness of advertising campaigns.