Max Duration of Sitting?

[UtopiaExpert]

So a teammates of mine has been very busy work-wise this age, so I sat out the first 3 weeks of the age for him. Now we're a couple of week on, and I asked him to let me sit out a war for him again, but he told me he has reached the max sitting duration. What is this max duration? I couldn't find it in the guide.

[Runefire]

So a teammates of mine has been very busy work-wise this age, so I sat out the first 3 weeks of the age for him. Now we're a couple of week on, and I asked him to let me sit out a war for him again, but he told me he has reached the max sitting duration. What is this max duration? I couldn't find it in the guide.

3 weeks (21 days), is the max.