Question re: progress with abdominal muscles

Hey all -

Hopefully this is an easy question.

I may be required to take a physical fitness test for a job application. The standards are not public, but I was advised that it will include running, pullups, pushups and situps.

I have been doing pullups, pushups and situps on my non-running days. The problem is, I'm not seeing any progress with the situps. I don't think it's a recovery or nutrition problem, because I'm seeing good progress in the other areas.

Should I do situps every day? I know there are more effective ab exercises, and I know situps aren't that great for the lower spine, but I'm kind of "training for the test" at this point.

Thoughts?