MUST WILL SHALL

I’m trying to understand something: The alchemy that seems to permeate portions of my workplace that makes “shall” preferable to “will” or “must.”

Today I made an appeal to our own writing standard. Follow, brave souls, if you dare.

Here are the definitions I’m working with:

Must Denotes requirement. Will and shall are alternatives. Compare should and may.

May Denotes permission, not a requirement or recommendation. Do not confuse with can, which usually denotes ability. Compare shall and should.

Shall Denotes a requirement. Will and must are alternatives. Compare should and may.

Should Denotes recommendation. Compare shall and may.

Will Denotes requirement, but is more dependent on sentence structure and tone than must and shall, which are alternatives. Compare should and may.

I want to concentrate on must, shall, and will, but included may and should since they are referred to in the definitions.

I feel like, looking at these definitions, that must, shall, and will are synonyms. They mean the same thing. Even taking in the added wordage that will’s definition brings into the situation, I fail to see the difference between the three words. (Will’s extra wordage could, in fact, apply to shall or must, so I see no reason for it to be there. The meaning of all words is dependent on sentence structure and tone. And tone is something we should weed out of technical documents as much as possible.)

Yet I find myself between the proverbial rock and hard place, regarding these words. The rock, engineers reasoning (I believe correctly, based on the definition discussion above) there’s no difference in meaning, and the hard place, preferring shall to will but more importantly gatekeeps what wording is blessed and what wording is frowned upon.

I tried looking at what others are saying about must will shall, and I found a lot of people either throwing their hands up and saying, "Yeah, there's no difference," to "there is a difference because reasons."

This is my favorite.

He seems to favor shall to will, but I feel like he cherrypicks his reason, denigrates opinion that varies from his own while he opines that he's right.

Wikipedia drones on about English modal auxiliary verbs but doesn't really accomplish much in telling me the difference either.

I don't see winning any battles here, though. I shall have to concede. Because this is all I'm really getting: