I think its wrong to say either side as advantage as they clearly are both balanced out by the positives and negatives or either all finishing same time or all finishing different times.
I think the nature of wars and the set times is a difficult thing to combat if he made it so wars could be arranged by the attacker or occur as and when this makes it hard for the defender to be ready but clearly this is more realistic as America wouldn't tell Russia there going to attack on X day X time. this could only ever change to this method if the defenders had the ability to deploy some defences to counter the fact they are not people logged on ready to fight.
However on the flip side which we currently have is arranged times which means it gives everyone the same amount of time to prepare granted this still makes a hard for defenders as they have to ensure they have enough people to defend on the said X day x time but at least they know it's always a set time in the current setup. There are no defences as the walls and archers are pointless at some of the walls and are not consistent across all walls.
The extensions have helped liven the wars up this is clear to see as a long time player and once a member of the guild that dominated the server before we left we can see this so I don't think they should go but maybe could be tweaked..
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Surely this is bullshit as your not allowed to fight them anymore....but yet still enjoy letting them take items your guild members drop