How Many Times Do You Have To Listen To Understand A Piece Of Music?

To quote Beefheart, "When It Blows - It Stacks."

That is all ye know, and all ye need to know.

It varies by song obviously some are more accessible than others. Countless times I've decided a song was the best on an album only to later consider a different song I didn't care for originally best on an album.

Classical music and good jazz—if it’s music that grabs me: hundreds and hundreds of times. In my case, Ralph Vaughan Williams, Charles Ives, Charles Lloyd and Charlie Mingus. If I listened to these in vinyl I would have worn them out by now. In fact I did wear out Three or Four Shades of Blue back in my turntable days.

Did you ever understand Picasso? There you go!
 

it is not meant to be understood by you. It has meaning to the artist. Not necessarily to you