I've had some success writing certain explicitly technical documents, with a style guide provided to the LLM that it can match, and then going over it by basically iterating on every sentence in the document and asking "can this sentence be removed?".

Style guides are a big tools people are missing out on. It isn't enough to say "write concisely and technically". Give them a sample. Yea verily these many 5 or 6 years ago, "style transfer" was a big thing that early LLM tech was doing. It's still very good at it.

That said I still tend to cut out at least 25% of the resulting verbiage and adding back another 10% or so more of my own original content even under those circumstances.

Where it has been really helpful is that I tend to want to write in a conversational style that doesn't seem to match most people's expectations of a technical document. The LLMs let me write my way and style-shift it into something closer to what people expect. And LLMs, since let's be honest they're the primary audience nowadays. Which I am not even upset about; I'd rather 5 LLMs read the architecture document than the amortized .2 or so humans I could expect in the same circumstance 5 years ago.

Which also implies, in many cases, I am feeding the AI as much text as I expect to come out, or in some cases, even more, as I am describing context, reasoning, and other things that may impact the writing but are not necessarily repeated in the final text. I factored out a lot of the context into my user-level CLAUDE.md which has helped cut that down a bit.