Dude, if you count every exercice possible in a training program you'll likely come up with several thousands and you might be surprised to learn that I don't use most of them.
My mentality is to use the least amount of exercises to get the job done. I'm not one to include every single possible exercise or method in a program and i think that coaches who do that have a really bad understanding of the human body.
Hollow holds like planks are fine at some point in a training plan. To me they can be a bit useful at the stage where someone is capable to contracting his core muscles properly as a way to bridge going from learning to use your core muscles to training them for performance.
But once you can do a hollow hold and hollow rocks for 40 seconds or more with solid form i see no reason to keep training on them at all, just a waste if training time. At that point you need exercises that will challenge the core more, like loaded carries, swings, etc.