Danish commas are optional in the way that Kingscote has volunteers.

I'm beginning to feel that I don't know anything like enough about comma rules/conventions in any language at all. Clearly tonight's time-wasting on the internet needs to be about the comma in English. It feels that it ought to be easier to move from a meaningful comma system to a rigid grammar one because the latter just requires you to learn the rules, but of course that might depend on how many rules there were ("On a Monday after the full moon, a comma must be used before all conjunctions").