maybe. It really has to be tested. I don't think its 3 weeks. I didn't say both, I said, either 0% and spawn day 0. or 10% spawn 3-7 days later.
Both is just totally unfair, and doesn't make sense.
The main point, is to give a better, more realistic cooldown, and yes, a kingdom should lose fiefs if they lost in the open field a decisive battle. Don't forget, sieging 1 fief takes about a week (more if you are using siege weapons for the player for instance). I don't think 3 weeks is half a kingdom honestly, I have played a lot, maybe 14 in game years. Maybe at the end end end game it could be like that, but at that stage, kingdoms have multiple armies (and so losing 1 doesn't massively change anything, especially given the current re-recruiting/spawn rate!!!!)
Like I said, its worth a test, and I think you have to make big swings for changes and then re-adjust, I don't think the current mechanic is any good. As I said, 20 lords can respawn, 200-300 troops + start recruiting asap. 300 is a lot at the high end!!!!