As you’ve no doubt found, cork takes an engrave very easily. I bet you could defocus and sacrifice a little LPI like @ekla said and still get really good quality. Depends on the specific art you’re doing, but yeah reducing LPI is going to be your biggest time saver by far.
There are other options, too, like traveling saleman solutions, halftoning, and other sorts of custom lines, you can do some really unusual engraving to get faster/unusual results, but it’ll all be really subjective.