It is folly to single out a single century, for one century builds on the next and to ignore what came before removes vital context for how you got there, removes the contemporary context and what was on their minds and governing their actions in that given period and finally it makes things seem almost unheard of or unprecedented when in reality such was merely a cyclical occurrence or otherwise recedes into the backdrop when presented alongside similar events.
I agree with you about the folly of singling out a single time period. But for most people who like history, there's a specific era that interests them the most. Mine would be early modern Europe, but of course that doesn't mean I ignore other periods of history. In fact, one of my favorite things to do is to make comparisons across periods. For instance, I've found many parallels between early modern European diplomacy and contemporary geopolitics in the Middle East.
I'd also add that focusing on certain aspects of history at the detriment of others is equally foolish. There are many people who study the politics and warfare of the past who completely ignore social and cultural history, or vice versa. Like Jacques Barzun, I deplore this "gangrene of specialism". History should be viewed as a whole, with none of its constituent parts left out.
Yeah I agree
That's why I would have had a hard time studying history. I wouldn't know what to specialize in. There's just too much that's interesting in order to totally focus on one small bit of it.