Dont mean to be harsh, but I'm not a fan
The problem is, whoever devised that routine has clearly got no basic knowledge of training because they have made the same rookie mistake in training the abdominals, they havent realised that the Rectus Abdominis is just another muscle, and therefore should be trained accordingly.
For example, would you train your pecs to the same extent of that programme, but substitue the exercises for relevant ones? No of course you wouldnt, because you would get to around the 4-5th exercise and it would lose its quality.
What are your goals that you are looking to achieve with your abs? because you stick to exactly the same principles of a regualr routine, 1-6 reps, 4-7 sets for power/strength( change tempo accordingly), failing on the 6th rep or lower
8-12 reps for hypertrophy( muscle growth) 4-8 sets with a tempo of 412 (4 seconds to lower, 1 second of 'rest' 2 seconds to contract) failing in no more than 12 reps
Or muscular endurance 15-25 reps 2-4 sets same tempo.
Most people are looking to be able to perform more reps of an exercise eg sit-ups, so therefore the endurance rep range would be used, if however you goal is to try to get a six pack, your better sticking to the Hypertrophy scale, as this will cause the abs to grow bigger, therefore making them appear more defined, especially if you thrown in some HIIT and good diet!
Bit long winded but hey....
KODE
