Vary Stance or Hand Position
Although true research is sparse, both anatomical and biomechanical evidence supports the need for changing both hand and foot positions, as well as seat angles, on exercises throughout your training cycles. Also by creating these variations, support musculature (read: stabilizers) will improve as will your overall length and variety of muscle movement. More angles, more fibers, and longer ranges of motion, means greater strength. And one final thought; making simple adjustments adds tons of exercises to keep your workouts both challenging and stimulating, so it is less likely for you to overtrain and/or become bored.