Get your upper back off the top of the bench. This allows the scapula to move with more range of motion, allowing the pecs to get into a more lengthened state.
Keep your palms forward and bring the dumbbells back toward your ears, not down to the side of the body. This also puts the pecs into a deeper stretch.
Use only a slight bend in the elbows. Most people get way too much fixed elbow flexion with flyes, turning into more of a half press/half-flye type of movement.
Whenever you can make a workout more time-efficient, you're stacking the odds heavily in your favor. Not only do you complete your training in less time, but you've also got more time to recover before the next onslaught!