Yeah after 20 hours the 2 DR would be 1, after 40 hours the 1 DR would be 0.5, after 60 hours the 0.5 DR would be 0.25, after 72 hours it would be erased. So DR counters will now include 3 days worth of attacks. If the attacks are 71.9 hours old that's probably still 0.15 DR or so still remaining of the original 2 DR.