Exercises Which Leads to less Effectiveness due to Unsafe Moves

Lat Pull-down Behind the Head
People with mobile shoulder joints can keep their spine straight to do this exercise properly. If move done wrong can lead to severe complications including shoulder impingement syndrome or even worse, tear in the rotator cuff muscles. And if the bar hits the back of the neck, it could even injure cervical spine vertebrae.

Exercises Which Leads to less Effectiveness due to Unsafe Moves
Safer method
Pull–down machine, lean few degrees back, use grip more wider than shoulder, and bring bar down in front of your body to the breastbone, pulling shoulder blades down. Contract your abdominal muscles to stabilize the body, avoid using momentum to swing bar up and down. The lat pull–down works both on lower back and upper back muscles.

Military Press Behind the Head
In this move, lift the barbell above shoulder then behind the head down, it causes the same problem as the lat pull–down behind the head.
Safer method : keep the bar in front of head. Weight should not be lower than the collarbone and keep your upper body upright while standing. this exercise can also be done in sitting.

Upright Row
The problem: Pulling weights, barbell, or a weighted cabled bar under your chin can lead to nerve compression in the shoulder area, shoulder impingemet and nerve damage. Safer method is Instead of doing upright row, work your shoulders with a lateral or front shoulder raise, lifting weights out to the front or side of the body. Keeping the slight bend in your arms.