yes, you should add the relays you want to publish to; I didn't want to dictate this from the app itself, so it defaults to choosing the relays you have configured, but you should add any other relays you want 😉
Discussion
Here is another item discovered recently. Was not able to see any published posts, or scheduled posts. Upon refreshing the page, clearing cookies, clearing history, etc., still no posts were visible.
When another "test" post was made, using send now, it then displayed all the published, and scheduled posts.