Oh yes, they take time to craft. Dreams and nightmares are built based on the needs of dreamers. As they change, so too must what the Dreaming contain. Which isn't to say that some dreams might not end up in more than one dream - many have delighted in those flying fish, for instance. It's more that some dreams and nightmares get retired and new ones take their place, and ones that have been retired might return or be amended. It's an ever-ongoing process.

I thought as much, though I didn't want to assume. Not that I've experienced a good deal of your world's legal system.