The Tradeoff Between Breadth and Depth
Answering this question may require more self-awareness than I am capable of. But let me point out one issue I struggle with, using an excerpt from an old article on My Rules of Thumb:
I'm an econ graduate from the Philippines. I am one of your admirers as a professional economist and as an excellent writer as well. I really like your blog, and I wish the answers to my questions here would be published there.
One thing I've noticed, you haven't told anything about your frustrations or hindrances (or even your weaknesses) to getting to where you are now.... Is it all intelligence, or your attitude matters as well? Did you confront career/professional problems, what are those, and how did you deal with them?
Having broad interests works well for bloggers, undergraduate textbook authors, and White House policy advisers. All three jobs require breadth, compared to most academic research, which is often deep but narrow in scope.
Throughout my life, I have been blessed with broad interests. (Or, perhaps, I have been cursed with a short attention span.)
As a child, I had numerous hobbies. I collected coins, stamps, shells, rocks, marbles, baseball cards, and campaign buttons. For pets, I had turtles, snakes, mice, fish, salamanders, chameleons, ducks, and, finally, a cocker spaniel. In high school, I spent my time playing chess, fencing, and sailing. I have long since given up all these activities (although I do have a border terrier named Keynes.)
As a college student, I committed myself to a new major several times each semester, alternating most often among physics, philosophy, statistics, mathematics, and economics. After college my path was indirect and largely unplanned....
My broad interests (short attention span) help to explain my diverse (incoherent) body of work. My research spans across much of economics. Within macroeconomics, I have published papers on price adjustment, consumer behavior, asset pricing, fiscal policy, monetary policy, and economic growth. I have even ventured outside of macroeconomics and published papers on fertility with imperfect birth control, the taxation of fringe benefits, entry into imperfectly competitive markets, and the demographic determinants of housing demand. None of this is part of a grand plan. At any moment, I work on whatever then interests me most....
Of course, breadth has its costs. One is that it makes writing grant proposals more difficult. I am always tempted to write, "I want to spend the next few years doing whatever I feel like doing. Please send me money so I can do so." Yet, in most cases, those giving out grant money want at least the pretense of a long-term research plan.
The greatest cost of breadth, however, is lack of depth. I sometimes fear that because I work in so many different areas, each line of work is more superficial than it otherwise would be. Careful choice of co-authors can solve this problem to some extent, but not completely. I am always certain that whatever topic I am working on at that moment, someone else has spent many more hours thinking about it than I have. There is something to be said for devoting a lifetime to mastering a single subject.
But it won’t be my lifetime. I just don't have the temperament for it.
If I had been much broader than I am, I would have been so shallow that I couldn't have managed an academic career at all. I suppose I could have been a journalist.