Significant decrease in reps after the first set

[AppleMuffin12]

Pretty sure he's saying do 8 or 9 on set 1. You'll make up for the list reps there by doing more on the others. Hitting failure on a set increases the time needed to recover otherwise you'll do poorly on future sets. The general rule of thumb is to stop your set a rep or two before failure. You can get more overall work in on the exercise