First of all some quotes from wiki:

E621/E926 have a hard rate limit of two requests per second. This is a hard upper limit and if you are hitting it, you are already going way too fast. Hitting the rate limit will result in a 503 HTTP response code. You should make a best effort not to make more than one request per second over a sustained period.

I write script and forgot to add rate limit to not get 503 errors, but it works (before I wrote bash script. There is no rate limit to). Wanted test that. I sorted post link by most smallest (all 75 posts is 290 Kbyte. How many porn there can be in 1gb?) and downloaded all this via file downloader. File downloader say that getting information about file of 3 link same time. Are i am doing wrong or rate limit only for page not for source? All file in place.