Home theater subwoofer equalization

If I want to equalize my subwoofer using Onix R-DES, is there a range of frequencies that I should focus on? I know it covers 16 - 120 HZ, but should I be focused on a narrower band within that?
Where are you crossing the sub at? If its 80HZ for example I dont see any need to extend it out any further than a bit pass your crossover point.