The other day I was editing a document in a zoom meeting while on shared screens as a work group prepared for a presentation. I was working quickly to meet an urgent deadline, and someone called out that I had inverted a pair of letters. As I backspaced quickly to retype the letters correctly, I said "I always feel like I shout use cut the offending letter and paste it back in the correct place." Everyone on the call looked at me with puzzled expressions, except the other writer in the group. She just laughed and said, "I get it. Every letter is important."
That's one of the reasons revising your own work is so difficult. We're emotionally invested in every letter, every sentence, every scene. It makes it terribly difficult to read our own work dispassionately, with the cold, heartless eye of an editor. When I work on a novel, I put an incredible amount of back story into the manuscript. I can keep a calendar document separately, to keep timing straight, and of course, a listing of characters with minor biographical data, but I can't develop character backstories as a separate document. For some strange reason I discover them by writing flashbacks, having characters remember or recount something, or just writing them as part of the action and realizing it can't have happened in this timeline, but it needed to have happened at some time for that character to be who he or she is.
To cut a scene that is pivotal for a character's development hurts. First, there is the emotional pain to cutting all these letters that are so important, especially if I have revised and edited the scene multiple times in different drafts and I'm just now realizing it has to go. But it's not just that. Cutting a scene that important in a character's development means there will be much more writing to do. The writer has to understand where the manuscript that back story is going to resurface and then build in along the way the clues to the backstory, so your readers don't throw a fit (or your book across the room) once the action happens. I liken it to when you read a murder mystery and the killer is revealed to be a character who made an appearance in Chapter Two for a few hundred words and then was never heard from again until the moment of the reveal, and the motive is some defect in the victim the reader didn't ever know. I may want to surprise you with something, but I can't blindside you or it won't feel true to the character. If your characters don't exhibit an internal truth, even in their inconsistencies, people won't continue to read your books.
I've said before that my characters are real to me, living their lives in the pages of a book and I can't force them to do something they wouldn't do without me at the helm. It turns out letters form the skeletons of my characters' bodies.