“Always leave them wanting more” is a quote that’s been attributed to P.T. Barnum, Walt Disney and even the American songwriter Bobby Womack. No matter who said it, it makes a lot of sense.
If a composer writes too little, his or her stature can grow. If a composer writes way too much, his or her reputation can decline.
Let’s look at the extremes. Here are two French composers whose lives and output prove the point.
Darius Milhaud, the Man who Wrote too Much
There’s not much doubt that Milhaud (1892-1974) was a composer of the first rank, or nearly. Subjectively listening, his works range from top-notch (the ballets La Création du Monde, which is possibly his most unique and strongest work, and Le Boeuf sur le Toit) to the somewhat pedestrian (many of his chamber works).  Milhaud was also historically important. He was a member of les six, and his composition students included William Bolcom, Philip Glass, and even Dave Brubeck.
When you discover an individual Milhaud composition, like Scaramouche, you are apt to be delighted by it. Does it have the individualistic voice or panache of Poulenc? You tell me, but I don’t quite think so.  His songs don’t have the innate charm of Poulenc’s either.

The problem could be that Milhaud wrote just too much stuff.  You can check out a list of his compositions HERE. This guy wrote a staggering number of songs, orchestra works, choral works, chamber works. He even produced more than a dozen operas, including La mere coupable,which is based on Beaumarchais and continues the story of Mozart’s Marriage of Figaro.
Now, you could argue that other composers, including Mozart, also produced vast bodies of work. Yes, you could. The problem is, Mozart was Mozart, and his works are stylistically and emotionally very diverse. You can happily listen to a Mozart string quartet in the morning and to his Requiem in the afternoon, and feast on the variety and newness of each musical idea. Milhaud, less so. After you’ve listened to five or six of any of Milhaud’s works, that’s enough for a while. It all starts to sound the same.
Henri Duparc, the Man Who Left them Wanting More
At the other extreme of the productivity spectrum, we have the French composer Henri Duparc (1848-1933), whose fame rests largely on 17 remarkable songs that he composed before he was 37 years of age.  He lived a lot longer than that but for some reason, he stopped composing young. There is a legend that at some point in his later years, he destroyed a number of works because he doubted their quality.
He was wrong. His songs have a unique voice, and more than hold their own against those composed by Fauré, Debussy, Chabrier, Hahn, and other great French composers of art songs. Part of what makes Duparc’s songs so extraordinary is that he most often selected texts by extraordinary poets like Baudelaire, Théophile Gautier, and Sully Prudhomme.
I would offer the opinion that the beauty of Duparc’s settings of poems by Charles Baudelaire exceeds even that of Debussy’s highly regarded Baudelaire songs. Let me also put in a personal plug for DuParc’s “Phydilé” (to a text by Leconte de Lisle), which I think might be the most beautiful French art song ever composed by anyone.
If you are unfamiliar with Duparc’s songs you are lucky, because a wondrous new world could become yours when you listen for the first time. I would suggest listening to these songs performed with piano, as the composer created them, not in the iffy, overblown orchestrated adaptations.
Here are some suggested videos to watch.
“Chanson Triste” sung beautifully by the wonderful soprano Sumi Jo. 

 “La vie anterieure,” one of Duparc’s Baudelaire songs, performed by the great French soprano Regine Crespin

“Phydile,” one of the most beautiful French songs ever written, sung by Stylvia MacNair:

“L’Invitation au Voyage,” another of Duparc’s astonishing settings of Baudelaire, sung by Kiri Te Kanawa:

So, could it be that Duparc, with his 17 songs, is a better composer than Milhaud, with hundreds of compositions in his catalog? Maybe, but that’s not what I’m suggesting. I’m just wondering whether Milhaud would be more appreciated today if he had left just a few compositions instead of miles of them.
I don’t know. You tell me.