I love chalk and talk but it puts a lot of load on the speaker. My Electricity and Magnetism professor basically pushed it to the limit I think. He had a carefully cultivated temper that was bad enough to keep 100 students totally silent for 50 minutes and he used about five different colors of chalk, but there are limits to what you can scrawl out on a blackboard.
You can distribute written documents, this gives you maximum opportunity to convey information, but you can't force people to actually read them. Going from a paper memo to email exacerbates this I think. Best case scenario, you can present very clear and well structured information but if you go past two pages you have to wonder if anyone is really paying that much attention. As a "best case example" I'd look at something like this memo that Robert McNamara wrote to LBJ about a month after LBJ took office: https://www.mtholyoke.edu/acad/intrel/pentagon3/doc156.htm . A benefit of written work is that you are committed to your words. But: creating a concise and readable written document that will effectively spread your thoughts is excruciatingly difficult. You can't write a book of background info every time you have a staff meeting.
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About remembering that you have a rough model though, I think the key thing is that when you realize that there is something you are interested in measuring and once you have a model then you can start looking for quantities you can actually measure to (in)validate and tighten the model. Always be model checking.