The superfluous can be unnecessarily distracting from that which is both essential and adequate.
Steve Jobs
Jonathan Paul "Jony" Ive — Chief Design Officer of Apple — once said focus to Steve Jobs meant not just saying no to unimportant things, but sometimes even to a few important ones.
"When you think about focusing, you think focusing is about saying yes. No. Focusing is about saying No."
Steve Jobs, Apple Worldwide Developers Conference (1997).
Robert Kiyosaki
"If you have any desire to be rich, you must focus. Do not do what poor and middle-class people do: put their few eggs in many baskets. Put a lot of your eggs in a few baskets and FOCUS: Follow One Course Until Successful."
Robert T. Kiyosaki, Chapter Seven: Overcoming Obstacles, Rich Dad Poor Dad (1997).
Warren Buffett
“Bill [Gates] and I, his father, many years ago, right after we met, had us a group of about 20, write down on a sheet of paper one word that we thought accounted for our success, and Bill and I, we may have met twice, didn’t know what the other one was writing, and we both wrote focus.”
Warren Buffett, CNBC (2016).
Buffett has spoken extensively in the past about how excessive diversification in one's investments can be counterproductive.
GrahamValue
GrahamValue does a complete 17-rule Benjamin Graham analysis and nothing more.
This is based on the same kind of conviction in Graham's framework that Buffett, Seth Klarman and Irving Kahn have expressed.