As much as I dislike 15 years, I would rather have 15 years truce than any of these abominations:
1. faster recovering manpower
2. faster decreasing WE
Johan, if you decide to change 15 year truce, don't go back to EU3. Simply scale it to 12 years or something.
I believe point 1) and 2) should indeed not be changed. As it currently stands it recovers quick enough to be of use after a couple of years ( not counting nations that inherintly gain bonuses anyway ).
Possibly a few things that could work if one wants to look at truce timers could be:
- introduce an idea that removes a defined number of years from the maximum of the truce in the peace deal just as nationalism works right now ( basically one could take 12 years as per your example here )
- introduce an idea that reduces the scaling of the truce timer ( 15 years maximum still ) but with - further - reduced truce time values below a defined threshold ( for example a peace warscore of let's say 66% - after that scaling will increase to until 100% with 15 years is reached )
This way, players who'd like to go to war often, can take that specific idea and furthermore nothing will change for those that rather play economy or trade focused.
Obviously that just some ideas I've been throwing around in my head for a while. I've played a couple of games with 15 years and it didn't really influence my playstyle at all - mind you with big nations though. I rarely play smaller nations unless it's for a specific challenge , i.e. an achievement.
Generally, to answer Johan's original questions:
1) Yes, since I normally take large swathes of land as a large nation. This is my main way to expand, thus larger truce timers exist most of the time.
2) around 40 seconds per year