During a gang war (war time) they would switch up a couple of the positions. The main one being the war-time consiglieri, because often times they would bring somebody who had alot of past experience during gang wars. Tom Hagan didn't have any war time experience so that's why having somebody else (i forgot who) being the war-time consiglieri would be needed. Better advisement through experience, I suppose.

Another thing i noticed during war time is that the hammer usually get exhiled after a major offensive. In the Godfather they exiled Michael Corleone, In the Last Don they exiled Pippi De Lena after his offensive on the Santadio family, and in Omerta they exiled Astorre Viola for a little while.