Hello friends,
I'm writing a simple Python script which retrieves the lists of tags from searched posts (posts.json), and downloads the posts themselves (located at static e621 net). Do each of these downloads require a pause before another post can be downloaded? Is there an alternative way to download them in bulk? (say, all 320 posts in a single page)

Requests to static1 aren't rate limited, you can even have multiple threads downloading (though at some point the network layer will stop you, test to see if it actually helps speed). Other pages including posts.json are, though, as specified in the API documentation.

There is no way to download the actual post content in bulk, at least from e621 directly.

topic #37724 You can also check if there's torrents 'somewhere' like these if you plan on downloading them in bulk.