Holding the standard plank for ten seconds or longer is useless according to Dr. Stuart McGill. Unfortunately, many people still try to do planks for time.
A better way to progress this core exercise? Make it harder. The cable plank press will help you take your core strength to the next level, and you'll even build some extra upper-body muscle.
When do you do low reps and heavy weight? What about higher reps and light weight? Read this and finally feel good about writing your own training programs.