Against a 10-minute running clock, complete:
800m Run
40 Pull-ups
40 Burpees
then, with the remaining time, AMRAP Squat cleans (225/155)

Score: Squat Cleans

If you have never failed a rep on a heavy day, you are missing out on training. 

If you fail 3 out of 5 attempts on a heavy day, you are missing out on training. 

The same is true for Met-Con days, if you have never failed a muscle-up or a clean because you have paced the workout too well, you don't know where your threshold really is. 

If you start going into your workouts with a practice mentality, where it's okay to fail a rep, and not be perfect you will learn so much about yourself and your movement.