Actually, I often use this method with the big lifts but mostly as a tool to improve technique.
The slow eccentrics increases activation of the motor cortex which leads to better motor pattern programing. It also forces the body to control the weight at every point in the range of motion.
Finally, it’s a good tool to strengthen tendons.
The isometrics allow you to strengthen key portions of the lift and teach the body to stay rigid in the position trained, which is iportant when facing a sticking point. It also allows you to focus on technique more.
Then you do the regular reps right after the paused reps and slow eccentrics, which makes it more efficient to apply the motor pattern developped with the slow/paused reps.
Basically, this approach prepares the body for heavier lifting by improving technical efficiency, teaching you to stay tight, build up tendons and muscle.
In the EOD plan, it could be used as the main assistance exercise, but using the same lift as the primary movement, but with this omni-contraction technique for 3-4 sets…