if you do box squats and pullups you are working your abs. a lot of compound movements will work the abs.. so if you are doing your compound lifts then you are g2g, if you aren't then you blowing a lot of opportunity to work sub muscles.
having said that i might isolate them once a week for a few sets. I will leave dedicating an entire workout to the abs for the females and the young skinny 8 pack dudes though.