I think you know this person. And the term "quit while you're ahead" means nothing to them.
Nor do any of the following proverbs which, though slightly different on the surface do in fact advise the same thing:
"Brevity is the soul of wit."
"It is the silence between the notes that makes the music."
"The space between the bars keeps the tiger in."
"Bow out gracefully."
I am sure you sense the pattern now, and can think of even more examples of this sentiment. That sentiment being one of perfectly timed restraint.
Believe it or not, my friends consider me quite a funny person at times. This may come as a shock to some of you, because you may not be able to imagine me working a room for laughs. And you would be correct. I never work a room for laughs. I don't say things that are even intended to be funny or witty every chance I get, and even when I do, I say them and leave it at that. If a whole room is laughing at something I say, I don't feel the need to keep saying it, or adding on to it to get even more laughs. Not that I have never went on a sustained presentation that others found continuously amusing, but in those cases the story or stunt had on obvious beginning, middle and end. People laughed at the journey. But in most cases, I am content with the knowledge that at a given moment, I made several people laugh and that a moment in the future will come when I do so again.
Even though I could probably coax more laughs out of whatever group of people I find laughing at my antics, hitting them over the head with how funny I am being feels like an insult to the wondrous, mysterious honor one receives when they make people laugh on purpose. No, it's the down time of quiet simplicity or quasi-stoicism that takes place between the amusing moments that makes the laughs more special. That goes for professional entertainers as well. Few comedians are more annoying than the ones who are one constant, loud, drilling scream of joke.
Put another way, the secret to being funny is being willing to sometimes not be funny. To have an "off" setting. Even most of the time, I am not funny to most people. And because I embrace the times when nobody is laughing, and I am not trying to make them do so, I get more out of the times when I am going for the occasional laugh.
Not that this applies only to humor and wit. I think one of the essential ingredients to any kind of success is to not be "on" all of the damn time. By that I don't mean making a mistake, or being imperfect in your efforts, which will happen to everyone. I mean a total cessation of effort. Whatever you enjoy, create, or desire cannot take up 100% of your focus. You can't always be selling, advocating, relieving or whatever. Your success in any given endeavor is directly proportional to how willing you are to spend time not being/doing/saying whatever it is that drives you.
Want to be funny? Take time to be serious. Do you want people to be respectful to your position? Throw in some humor sometimes. Want to be generous? You'll have to learn to be selfish at times.
The list could go on forever, but it doesn't need to in order to make my point, which is to know what you like, work to get it, but be willing to engage in times when you don't have it. Not due to circumstances or luck, but due to your own conscious desire to refrain from that which you seek. You'll be better off for it the next time you actively seek what you want.
Do you ever choose to not engage in something, to create that "space between the bars"?