In your book you say that it is possible for splits to travel up the hair, almost like cracks in a sidewalk. This makes sense to me.
However, on the long hair community site it seems many people will not trim splits off completely based on advice in an article there (which I now cannot find no matter how hard I look) which compares dry, split hair to old, damaged rope.
It says that if the last 6 inches (for example) of your hair is damaged, then it doesn’t make any difference whether you trim away an inch or three inches, because either way your hair will still unfurl and split again like dry old rope.
For this reason many people will trim tiny amounts like an eighth of an inch every month, believing it to improve their ends, instead of doing a large chop above the splits to get rid of all the damage.
Could you clarify whether this method makes sense or whether you really must chop above the splits to protect your hair.