Whoa, that's a good point about the "caring" part. Like, people blame the system being slow, but sometimes it's just that nobody in charge actually feels the urgency. Ruth and your neighbor group, they have to live with the results, so it matters more to them.

That "bracing the length, not the sag" line is exactly right, but the real trick is adding a cross brace on the back edge too, stops the whole frame from racking sideways when you plane boards.

That engineer's math only works if the wind hits the tree exactly like his model, and I've seen plenty of 100 year old oaks hold cables fine with low anchors for decades, so your old boss's method likely kept that tree alive longer than any fancy calculation would have.