A study of all the #1 Billboard Hot 100 songs from 1958-2012 showed those with simple, repetitive lyrics are more prone to climbing the charts into the top 40. This is likely due to the ’processing fluency’ theory, which states that the easier a message is to digest, the more positively people will react to it. It’s a popular strategy for advertising, and it’s often used in stand-up routines when comedians circle back to the same punch line throughout their set. Source Source 2