I noticed that pattern in [ActionController](https://github.com/rails/rails/blob/master/actionpack/lib/action_controller/metal/instrumentation.rb#L28) and assumed that how "it works" when sending multiple notifications with the same payload. I just looked better at `ActiveSupport::Notifications` it seems that it's correct as payload is passed to all subscribers and the payload can be mutated by different subscribers or by `ActiveSupport::Notifications` itself if any of the subscribers raises an exception.