In his magisterial cultural history of the last 500 years (From Dawn to Decadence), the late Jacques Barzun wrote as follows about the study of history (pp. 568-569):
Any writer of history aims at stating the truth, but that is only ancillary to the central role of the discipline, which is to present patterns and permit the welter of facts to be reconceived…. If one is well versed in the facts one may question the historian’s estimate of persons or deplore events that he celebrates, but these disagreements leave a vast edifice standing and not to be seen anywhere else…. The dissenter who says “it was not like that” is in the situation of friends passing judgment on another friend: “He did this, which means that.” “No, it doesn’t, because he also did that, which means this.” The dispute cannot end unless each side responds to the challenge: “Tell me what your standard of action is.” At that point, barring factual errors that both sides will acknowledge in good faith, each will retire probably unconverted. Such is the reason for saying that a reader of history must be a reader of histories – several on the same topic – and a judge at leisure on the points in conflict.
The same applies to the pursuit of wisdom: it’s not enough to study only one philosopher or one school of thought. Just as with history, life presents a welter of facts that need to be repeatedly reconceived and re-examined (recall Socrates: “the unexamined life is not worth living for a human being”). And a key tool for that mental and spiritual work is to reflect on human experience and the facts of your own life from multiple perspectives.
Indeed, the similarities between history and philosophy on this point might be part of why Henry St John (1st Viscount Bolingbroke) said that “History is philosophy teaching by example and also by warning.”
As to my own exploration of philosophies (or as I once called them the Minerval Arts), you might have noticed that these days I post frequently about Aristotle; that’s because I’m writing a book about his views on human flourishing. However, not only have I previously written books on Epicurus, Thoreau, Nietzsche, and Rand, but I’ve also read quite a bit about Montaigne, Spinoza, the Stoics, phenomenology, Taoism, and Confucianism (admittedly less about, say, Indian philosophy, existentialism, and Christian theology).
One of the wonderful but also challenging aspects of engaging in philosophy as a way of life today is that we have access to every major philosophical and theological tradition that has ever existed plus the multifarious schools of psychology, anthropology, sociology, and history. Although it’s impossible for any one person to integrate all of this knowledge into a seamless whole, having so many angles of vision can give us more comprehensive insight into the complexity of human life. Rather than seeing this as a liability, I prefer to see it as an opportunity for achieving greater wisdom.
Spoken like a true philosopher, I suppose!