Don't know shyt and have never had abs(working on it) but I think direct ab work is a waste of time unless your working out your core (planks, ab roller, or palloff press, I thought they were called cable crosses
). I know they all work your core but from what I've been told/read those are some of the most effective. Exercises like situps are bad for your spine and most of the work is done by your hips.
If you're a fat guy that wants abs, you can use your workout time and energy in better ways than direct ab exercises to reach that goal.
If anything I'm saying is wrong let me know.