I wrote a modern country song that has arpeggiated Verse that I play at 120bpm, and the Chorus and bridge plays at 128bpm. The song totally looses its feel if I try to play at a stagnate tempo even if I try to split the difference to around 124bpm. The Verse at 124bpm sounds like it is being rushed. The Chorus at 124bpm sounds like it is lagging.
The song is in 4/4. Is this type of small tempo swing back and forth fairly common?
I remember reading that a very high percentage of hit songs has tempo changes in them but I don't know if that is including very small tempo swings.