Pullovers should be part of any chest routine. Use them as one of the last exercises of the workout after other muscles are already fatigued.
Finish your next chest workout with dumbbell pullovers: 3-4 sets of 12-15 reps. Focus on squeezing the pecs to initiate the movement up from the bottom position and work on holding the squeeze throughout the rep.
Matt Phelps is hugely pissed about the term "failure" and what it really means. He thinks exercise physiologists have one idea while the guys in the trenches, i.e., the guys in the gym, have a different, more realistic idea.