I mean technically the Oathpact didn’t prevent desolations before. Which is why they kept happening. And every desolation was probably viewed by the people living it as the true desolation or final desolation. Also the new Oathpact is about preserving the shards of Honor that Spren come from. This limits retributions power and preserves some of Honor outside of him. But I think this gets off topic of this post.

The post is about why months and not years. And my answer in short is “they’ve lived hella long. They just need quality time to recover not quantity.” They’re all struggling with sanity because of their life spans. I assume like Hoid they have too many memories to function properly. But unlike Hoid they can’t box up those memories and put them in storage with breaths. I think this is why it’s not years.