This stuff is well preserved from reptiles and amphibians.
I would think that until you know how the stuff works I assume that it is all needed until you learn otherwise.
This is the “dumb boss” part of my “dumb boss / smart adviser” model.
The “dumb boss” is still pretty smart.
When you can program a robot to do everything a crocodile does using neural networks you can make the call on what parts are not needed.