Songs are getting shorter - probably as a result of streaming

"Popular music is shrinking. From 2013 to 2018, the average song on the Billboard Hot 100 fell from 3 minutes and 50 seconds to about 3 minutes and 30 seconds. Six percent of hit songs were 2 minutes 30 seconds or shorter in 2018, up from just 1% five years before.
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Why are songs getting so much shorter? Streaming is one the most likely culprits.
Payments from music streaming services like Spotify and Apple Music made up 75% all US music revenues in 2018 (pdf), compared to just 21% in 2013. Streaming services pay music rights holders per play. Spotify doesn’t say the exact amount it pays artists for each stream, but reports suggest it is somewhere between $0.004 and $0.008. Every song gets paid the same. Kanye West’s 2010 five-minute opus “All Of the Lights” gets the same payment as West’s two-minute long 2018 hit “I Love it”.
“[T]here has never been this kind of financial incentive to make shorter songs,” tweeted Mark Richardson, the former editor of the music criticism site Pitchfork. Stuffing more diminutive songs into an album is simply more remunerative than having a bunch of long ones.
Still, it’s hard to pinpoint exactly how much streaming has contributed to the recent shortening of songs. The length of pop songs had already been falling through the 1990s, before accelerating in recent years. Some music industry observers blame shortening attention spans—but there isn’t much rigorous evidence that our ability to focus has changed (paywall). Others believe that shorter songs may be a result of more consumer choice—songs need to be more compact and catchy to stand out in the crowd."

Source:  Quartz, 17th January 2019