Capturing all the imperial keeps should depose the current emperor. But, your factions top player should only become the future emperor at that moment. The actual crowning of the new emperor happens exactly 24 hours after the last one was deposed. Unless of course the faction loses all the imperial keeps before that can happen.
It's just my opinion that the time between pushing for emp and actually crowing is way too short and doesn't encourage prolonged fighting for the throne. Also, it's my opinion that if your faction can't hold at least one imperial keep for 24 hours, you don't deserve to become emperor/empress.
Another thing this might help is night capping. I understand players shouldn't be punished for playing during off hours, but they also shouldn't reap huge benefits for it either. If a group wants to push for emp at 5-9am while a lot of people are sleeping, then I should be entitled to defend it at whatever time I decide. A 24 hour delay would mean everyone can contribute to the assault or defense no matter what time of day they are active.
It's like how when you assault a keep, if you capture the farm, the keep doesn't instantly lose the upgrades that farm has provided, there is a delay so the owners of the keep can respond and recapture it. The 24hour delay would allow everyone in a campaign to get in on the action and help crown or depose a future emperor.
[DC/NA]