At the end of a Wildermyth chapter, you are told that the land experiences a number of Years of Peace before the next one starts. How many years of Peace you get depends on how well you did during the chapter, so Peace is essentially a reward for activities such as clearing infestations and upgrading defences. But what does Peace actually do? What’s the point?
Various character events may happen in the interval between chapters, but (with the exception of Retirement) none of them affect or are affected by the length of the Peace. So what advantages and benefits do you get from a longer peace? More resources? Skill gains? Region upgrades?
Nope. None of the above. Nothing. Nada. Having more Years of Peace brings you absolutely no advantages in terms of game mechanics.
One thing that does relate to the length of the Peace is that your characters age. A longer Peace brings them closer to their set Retirement age, at which point they stop adventuring. This is an interesting narrative beat, but not necessarily one you want to reach quickly.
So does that mean that you should try to avoid the activities such as clearing infestations that increase the Peace duration? Absolutely not, for two reasons: first, Peace is good! Wildermyth is a narrative and character based game, and Peace should be its own reward.
But what if you’re the sort of player who likes to minimax stats and optimise everything at a micromanagement level? Well, you probably wouldn’t be playing Wildermyth… But if you are, then you need to remember that although Peace is negative from a game mechanics viewpoint, the actions that lengthen the Peace actually bring rewards such as Legacy Points (LP) and resources. So you can think in terms of balancing the advantages of those actions against the character aging from the resultant Peace and attempt to optimise the trade-off.
Personally, I play Wildermyth as a storytelling game that happens to have stats. Peace is good, end of.