Running the rack is one of my favourite methods for overloading or bringing up lagging body parts.
To do it start at an easy weight and work your way up the rack, increasing by one weight increment each time.
Doing 3 reps at each weight work well.
Keep going up one weight doing the 3 reps each time until you fail to hit the 3 reps.
At this point start working your way back down in the same fashion until you get back to where you started. If you get it right each mini set on the way down should be close to failure as you fatigue more and keep dropping the weight.
Aim to pick the weights so you do about 5-7 weight jumps on the way up and on the way down.
In the video below is one "set" you could do two to four of these as a finisher or the entire workout for that muscle group.
Run the rack style sets also work great with pin loaded machine exercises such as leg extensions, tricep pushdowns and leg curls as the weight pins make it quick and easy to go up and down in resistance.
So in this video we have Ash doing run the rack with seated dumbbell shoulder press. I've got him doing only the middle two thirds of the range of motion. He doesn't quite lock out and doesn't quite touch his shoulders at the bottom. This is to isolate the delts more and keep them under tension for each lot of 3 reps.