Carries to Improve Overhead Strength & Stability
Ask around and most will tell you the bench press is the best exercise for upper body strength & development. Personally, I disagree. I truly believe that title belongs to the Overhead Press. Nothing says "strong" like picking something really heavy off the ground & hoisting it overhead.
The benefits to your upper body are massive, but it also provides a tremendous stimulus to your core. Use them as warm-ups, fillers, or programmed into the finisher. If the press is a staple in your program, & even if it isn't, overhead carries can play a huge assistance role.
The added time-under-tension will help improve muscle growth, strength, & endurance. .
The act of balancing while walking will torch your trunk musculature while improving single-leg balance & gait mechanics.
Adding the banded, bottom's-up, or javelin variations will increase the emphasis on stability & increase rotator cuff activation.
The fact that you aren't looking at the weight during the movement will increase activation of your joint proprioceptors, which provide the instructions your muscles need to stabilize the joint.