As my old art teacher used to say, "You work on something and it gets better and better and then it turns to shit."
Taoists discovered this phenomenon thousands of years ago and called it overdevelopment. And it's universal for all processes under the Sun. There simply isn't infinite progress in one direction, because it's a circle. The ideal way is to switch one circle for another at its peak development, but recognition of that point requires using the heart, not the brain.
This is a large part of the discussions in the first one or two interviews in Interviews with Francis Bacon by David Sylvester. Bacon talks about pushing to the limits of adding more to a work until it's good, and then if taken too far it ruins the work. And only very rarely can he pull it back around to good.
My wife is an oil painter, abstract expressionism, and she will constantly worry if something is done. And there have been glorious paintings ruined by one last thing.
"But there's a point where extra effort makes the work less good."
This happens frequently in mixing and mastering audio tracks. You pile up incremental changes that all seemed good at the time. Then you go back and listen to a recording from 20 revisions ago and it sounds better than your current "best" effort.
Sometimes that is because you need 60 more revisions to make it good - though you may have to go back to the start several times to figure out which are good.
I find I can churn away making revisions for a month and it makes a new, typically worse, song
I just saw Herb Alpert and the Tijuana Brass in concert last night (he's 90 and can still play that horn!) and one of the things he talked about was recording his vocals for This Guy's In Love With You written by Burt Bacharach and Hal David. He's a great musician but not much of a trained singer, and he said when he got into the studio, he sat down and did a relaxed first practice take, expecting he'd go and record one "for real".
Instead, they told him his first take was absolutely perfect - and it went on to be Bacharach/David's first #1 hit song.
Sometimes you get lightning in a bottle, and you just don't mess with it because it's perfect even in its imperfections.
And sometimes for some types of music they will intentionally re-do takes until the singer is a little hoarse and irritated to get a more 'raw' performance.
I don't think the phenomenon you're describing is a result of the amount of effort put into the piece.
If it was in muscle memory it would be repeatable feat, and it really isn't.
Some work is technically polished and you can see/hear the effort that went into it.
But there's a point where extra effort makes the work less good. Music starts to sound stale and overproduced, art loses some of its directness, writing feels self-conscious.
Whatever the correlation between perceived artistic merit and effort, it's a lot more complex than this article suggests.