You can also use generic events for leaders as well.
So, instead of saying "More reinforcements have arrived in the South", you can say "General Clinton has arrived in the South" (presumably with reinforcements).
It really is just a matter of taste in a large way, but by using generic events, you can get rid of a whole lot of noise in the event scripts, and the Local BoA file. Great for WiA too which has even more noise that BoA.
But just remember, when working with generic events, that could be used more than once during a scenario:
Always use Start Event 999 or the event may not execute.
Always use Fixed Date if you only want the event to execute one time.