I refuse to care about this. A single dash is all I will ever use. I see no possible reason to use the other two.
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It's not like you can reliably write these consistently by hand either without going over the top in length to make it extremely obvious.
E.g. some English language rule says that a comma or ending period of a non-quoted sentence goes inside the quotes if there's something quoted at the end of that sentence. That rule feels anti-intellectual to me, as if there's some misunderstanding of how hierarchical placement in one-dimensional space works (since something that's not being quoted is being put inside quotes)