Mathematically, if D3 is extrapolated to D1, to accomplish D3 goals, one needs to get to 35 to 40 rounds on D1 in 20 mins. This looks like getting more and more real around L4. Till L3, I didn't have to do more than 30 rounds on D1 to eventually pass D3 test. On L4, I am upto 32/33 rounds on D1 and still can't pass D3 test.
How many are rounds are you doing on L4D1?