Also, in primary/tournament/anywhere else, if currently after 24 hours, 4 attacks DR becomes 0, and now after 20 hours (18*1.1), 4 attacks DR becomes 2, isn't everyone always going to be in a lot more DR?

hm it depends on the average hit rate on a country, and the timing. If they're getting 3 hits per day or less, and the last hit was more than 6 hours ago, they have less DR than they previously would, for example.

Even if they were being hit 7x per day, but the last hit was more than 18 hours ago, they're fully 1 less DR than they would previously have been.

So no.