A query plan is created for every ResponseFuture in the __init__.
This is unnecessary In cases where _query is called directly (e.g., when we prepare_on_all_hosts ). We should stop creating these plans unnecessarily if possible/reasonable.
For the record, I think that it was done that way before the host targetting capability, which is relatively recent. Maybe we could just use the `ResponseFuture.host` argument you pointed and call send_request. To investigate...