I have read about occluded reps and stretching out at the bottom under tension, and have played around with it a bit. It does encourage growth, but it also takes a while to heal up. Dips should be done in strict form with no back hunching, or back imbalances can occur. Stretching the pecs out after fatigue isn't something a new lifter or out of shape person should try until they start to know their body better.