Yes it works this way: when in the template there is a block of posts (with its filters), the block can be configured to “stop” the newsletter generation is there are no new posts (after the last delivery date). So, if no other posts with tag “1000” are added, the generation should be skipped.
Just pay attention to the right configuration of the posts block. The “skip” options are available only when the block is used to create an Automated template.