Yes when someone else is forcing you to do situps in a school, smoke session or otherwise. When it's within your own control you should train smartly.
I agree, but I think I'll need it in a tough selection process(Like SFAS, CSS, UKSFS, etc). For example I'm going to apply to the FFL, after it I won't do more sit-ups till I need it again. But If I'm going to the Airborne School or to the Close Protection Training I won't need to do thousands of sit-ups. That's the point.
At least, I needed to do 75 sit-ups(2 minutes)at a minimum in my CPT's selection and most people failed it .