The logic that I meant was for sending out the emails. Typically, instead of looping over all of the users, you would check if the user has unsubscribed from the email, if there was any kind of time preference, using batch finds instead of looping through every user, etc.

I hold command and click and drag up to select multiple cursors for the number of items that I copied. You have to do something similar for the items you copy.

You're correct that indexing a low cardinality column like the Role may not be beneficial. 

While it may be annoying with Active Storage, it's probably best to let it handle the folder/file structure within S3. This isn't something that one should be touching in ideal worlds.

If you're on a Rails 7 Application, I would probably not create custom channels if you can avoid it. Hotwire's Turbo has gotten us so far to where a lot of the manual channels are no longer needed and can exist in the background now through Turbo.