I was wondering. Normally I always do side pulls and knee raises for obliques and lower abs, but aren't all of those hit with situps ?

I added them the last two weeks but don't like the increased volume so is it necessary ? Aren't the situps enough for all 3 parts of the abdominals ? I'm doing the 4 sets of 5 on a 45 degree incline situp station while holdin a 60 pound weight.