The idea of DRS is to counter the negative aero effect on a faster car following a slower car through fast corners. It should not allow one car to easily breeze past another like we saw today. So, the FIA should:
Use a simulator before each race to calculate the expected time losses in dirty air through each quick corner on the lap. Then, devise a set of short DRS zones on the straights following said corners, each of the exact length to counter the specific time losses.
This should hopefully counter the aero effect in a fairer way, and prevent the 'slam dunk' passes that occur when the DRS zone is all lumped together on one straight.