Before we discuss how this could be the case, some background on the type of attention spans that have been documented:
Transient attention span is about 8 seconds long, and is typically something that attracts/distracts - think ads & pop ups when browsing. With broadcasts the rule of thumb for dead air on FM, half the remaining listeners would flip to another station every 7 seconds in a long decay (AM, was about 30 seconds for the same thing). People will listen to under 7 seconds of a song to see if they will like it before finding another one. I wouldn't be surprised if a typical Social Media post gets about this level of scrutiny before moving on (or if a link won't open quickly, a few seconds later, the browser ios off on another one).
Selective Sustained Attention lasts around 20 minutes. Typically this means that you can focus attention on a task, meeting, musical performance or other focussed task without a break for about that long. If you like what you are doing, you can usually can pay attention for longer. And of course you can also consciously re-focus to keep at the task, though a small break might be needed. Incidentally this is why most hour meetings tend to degenerate or need a break if they stretch on for more than about half an hour. Church Sermons keep things changing about that quickly to hold the attention of the congregation.
This brings us to music.
A typical pop song is 2-3 minutes long.
An album side is about 20 minutes long (give or take)
A typical symphony movement is about 20 minutes long and will have 4-5 of them in a concert with an intermission halfway.
A typical music set in a rock concert would be 15-20 minutes long (with 2-3 of them)
A CD is up to 77 minutes long
When we were talking about silence in our last entry as making music more enjoyable, it could very well be that a small break every 20 minutes (or something that changes things up like a segment of a rock concert, or symphony) refreshes our minds, and lets us re-focus on the next side, or movement.
Some thoughts and questions we have, and are pondering:
If the CD is up to 77 minutes long, was the format doomed for not taking into account attention spans, making listeners distracted about a third of the way in, relegating the artistry to "sonic wallpaper?"
When streaming, with music being continuous, could that blow past our ability to really listen carefully due to the breaks needed to focus? Is it, therefore, a terrible medium for critical listening?
Did the LP "luck" into the ideal set length for holding attention - could the break every 20 minutes to flip an album, or find a new one to listen to, be an actual strength?
Could part of what we all love about vinyl be that we automatically get a break where we refocus and reset our listening, so we actually enjoy more of the music because we can actually pay more attention to it?
More food for thought ...