I agree with all of that, however, I still stand by; if you're writing a technical document/paper you should spell out all of them, it's just how I was taught.
It doesn't have to be a hard rule, but major topics of a subject should be spelled out, at least, then you're giving people something to work with in their web search.
It doesn't have to be a hard rule, but major topics of a subject should be spelled out, at least, then you're giving people something to work with in their web search.