Yes, conspiracy is a very common form of political behavior, because there have been several conspiracies throughout history. The one that comes to mind was the conspiracy to stab Caesar. There have been other conspiracies in which leaders have been ousted by their underlings deciding to remove them from office. This is common in politics.
No, in my opinion conspiracy is not a very common form of political behavior. While I believe that it is not a common form of political behavior this does not mean that I do not believe that conspiracy happens. I feel as though in general the public shall be informed of what occurs in time once everything has been resolved.