A "strategic" secession is against the rules? Like, Fontan-SoA? Or something different? Kind of curious now, as conquest and secession of duchies (or at a minimum a CTO) is almost necessary to make progress in some wars, particularly when it's an already large realm doing the conquering. DoA on EC springs to mind, though I'm not sure if that was secession or a CTO. Not that it makes a difference in my mind, the purpose is the same either way if you ask me.
I think the rule is a bit blurry. If you secede because your realm is just too big to be handled, or because you have no desire to keep the new land, like the secession of westmoor from Perdan, then it is fine. If you secede to enhance the effectiveness at destroying an enemy realm, it shouldn't be allowed. Fontan/SoA was a bit of both, as Fontan clearly understood without a secession they wouldn't have been able to take OR lands, and also because Fontan was simply becoming too big.
As a rule of thumb I believe it's always better to secede or colonize after the war that gave you the land, like Ibby and Doa, rather than during it, as Fontan/Soa.
However I'm afraid this is off topic maybe someone can move the posts to a new topic somewhere else more appropriate? I think it's an interesting argument to make some clarity on.
