I´m not sure we are at the same level of game knowledge. Your posts rise a lot of questions for sure. Lets improvise now a little: For NSing a target of your own size you need roughly 20-30% thieves for max gains depending on army size and army home or out but this is about average you need to send for max gains when you run 3-4 tpa. And you dont need to really max gain because sending 15% might give already pretty close to max gain. 20% of 5000 is 1K. You need to send about 1K thieves for max gain NS on guys at 1K acres. You need to time your incoming TD but its not like you care too much about the losses anymore at this point. I think you can NS just fine those 1K acre guys for a while at least. But you dont even need to do that because you can NS opponent chained provinces elites out and probably with much less thieves giving max gains. Doubt they have any WT left so should be very good success and decent gains too. You can destroy their offense.