Whether to specialize in a single subject, skill or activity (to “niche down,” in business terms) or to engage in various fields is a true dilemma, as there is no singe correct answer. Perhaps, niching down carries the higher probability of near-term success, while aiming to become a polymath promises more glory. I am not referring to glory in a conventional sense, or rather not only that, but generally a well-rounded and balanced personality and lifestyle, as well as the potential to eventually make a lasting contribution to whatever the field(s) of activity happen(s) to be (just think about Leonardo Da Vinci!)
I came across another appealing reason for diversifying one’s areas of interest in an interview with Stanley McChrystal, a retired 4-star US Army general. He mentioned that being genuinely interested in physical conditioning provided him with an area that was sufficiently separated from what he did professionally, so that even in the face of a crisis situation at work, he was able to think, “the workout today was excellent,” which provided a certain sense of stability.
I think that it is unreasonable to expect a constant rate of improvement at whatever we do, so it might be a good idea to cultivate multiple streams of activity, so that plateau periods in one would not negatively reflect on our overall perception of the situation.