War - by default place same champions in same places
How about the default (which can be easily changed) is to place the same defenders in the same locations, so that if the player does nothing except hit join and OK then it will be the same as the previous war.
Of course, if they weren't playing last war then not; if a champion is not available then not; but otherwise yes.
Because in most teams, most of the time, there's going to be very little change to defenders or placements; so why do 30 people have to redo it (and the officers check placements) every 2 days, over and over again?
If needed, offer a 'clear placement' button that takes them all off the nodes and back to nowhere.