Yes, that's right, a change to 3 days will also need the reward period to be reduced. There used to be a dual reward period before, 12 hours or 24 hours and then a 30 day. Since almost no rewards were allocated after 24 hours or so, and it was too complex to keep two periods, it was shortened rather arbitrarily to 7 days as a middle-ground between the two. Since then it's become clear that even the 7th day no real rewards are added, apart from hiding abuse, so going back to a 3 day reward period would make sense. But if the 7 day reward period stays, then 1 week, that's why I offered both options in my comment above.