I am confused about the bandwidth cost of realtime

[idle flax]

so according to the realtime documentation, https://docs.convex.dev/realtime the cached reads do not count towards database bandwidth.

So let's assume

1. I have a message component with title and content and id of 999.

2. I have 1000 people subscribed to message with id 999 using convex query.

3. The author changes the title of message id:999 to something else which would trigger change to all the subscribed users.

would the cost bandwidth 1000 times or just once and 999 people read from cache?

I understand that the subsequent subscription/query will definitely read from cache but what if it's all simultaneous like in this case?

Also, will paginated queries also be cached? so if I run a pagination in a chat app and if another user submits a message, if 1000 people are in the room would I pay badwidth only once?