Depends on how much bodyfat you have covering your abs. Abs take a lot of work and are hard to define.
If you're looking for definition, you'll get better results using resistance.
There also is no magic number or exercise that is optimal. (Example: For a newbie, they might kill themselves on that routine,...for a seasoned lifter they may be able to run math equations and make their shopping list out while doing them because it isn't challenging,... for others, their form is not correct so they're not gaining ab benefits).
Body fat over your abs is like frosting on a cake. You could make a really hard, firm cake, but if you still have that thick frosting over it, no one sees what that work accomplished.
If you have a lots of fat covering your abs, I would start with cardio workout to trim the fat down first.
And go on a Circuit Ab routin; for example, i do 10 reps of 10 different ab excercise continueously without taking a rest. The key is to do it slow and do it right.
I don't think doing MASSIVE amount of Abs will help ya get nice 6-pac. If you do it right, you'll see results.
Best of Luck,
Ps, its best to be on a healthy diet for best results.