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.