Wait, you've already made truce timers 5 - 15 years because of the same alleged problem. And increased coring and diplo-annexation costs.Revanchism
In EU4, a common problem for countries is ending up in a negative cycle, or 'death spiral'. What we mean by this is that a country gets attacked, has its armies wiped out and loses territory. Afterwards, it takes them a long time to regaintheir manpower and armies, during which neighbours will pounce or rebels rise up, and they never quite recover. As a way to try and address this and give countries a chance to rebound, we've introduced a mechanic we call 'Revanchism'.
I would greatly welcome this change, though, because unlike truce timers and increased expansions costs, it encourages a faster game phase. However, it's weird you had already tried 2 solutions for the same thing, and come up with a new one again.
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