Ab training

I've been hearing a lot about abdominal training recently, and went to search for some information about it, and I found this article. It suggests 7 incremental levels to train one's abs.

• Level 1: 3 sets of crunches
• Level 2: 2 sets of crunches + 1 set of hanging knee raises
• Level 3: 1 set of crunches + 2 sets of hanging knee raises
• Level 4: 1 set of crunches + 2 sets of hanging knee raises + 1 set of parallel leg raises
• Level 5: 1 set of crunches + 1 set of hanging knee raises + 2 sets of parallel leg raises
• Level 6: 1 set of crunches + 1 set of hanging knee raises + 2 sets of parallel leg raises + 1 set of full leg raises
• Level 7: 1 set of crunches + 1 set of hanging knee raises + 1 set of parallel leg raises + 1 set of full leg raises + 1 set of inverted scissors

Note: Each set refers to 15 reps. Rest time is 1 min between sets. Progression to the next level requires the successful completion of all sets in the current level.

I suspect I'm at Level 3, and I wonder what level I can reach. Guess I can include this into my training regime at the gym.