When it comes to strength training, a full range of motion is typically recommended for every movement in order to reap the most benefit. However, there are a couple of things which you must consider in your quest for size and strength.
Bodybuilders understand the importance of keeping tension on the working muscles and increasing the time under tension for each and every set. One advanced method they use to achieve this is called continuous tension sets, which is a technique that's in direct contrast to locking out every rep.
To do the continuous tension technique, stop right before lockout at the top of the movement and immediately move into the eccentric (negative) phase of the next rep. One way to further increase the muscular tension and metabolic stress is completing slow negatives by lowering the weight for a count of 3-5 seconds.
Here's what that looks like with dumbbell bench presses:
This method takes advantage of the continuous tension sets by keeping the muscle loaded while increasing the time under tension.
Eccentric training can be especially beneficial as this phase causes the most muscle damage and leads to greater rates of protein synthesis post-workout. Studies have shown that your body can tolerate up to 1.75 times more weight eccentrically than it can concentrically. (You can lower more than you can lift.) If you haven't been emphasizing the eccentric portion of your lifts, then you're certain to increase muscle growth when you do.
The great thing about this is it allows you to workout at a higher intensity and higher intensity means greater stress, which means greater adaptation.