Wikipedia. A userscript (or user script) is a program, usually written in JavaScript, for modifying web pages to augment browsing.

1. On desktop browsers userscripts are enabled by use of a userscript manager browser extension such as Greasemonkey or, much more better, Tampermonkey. Links:
https://www.tampermonkey.net/index.php?browser=chrome&locale=en
https://www.tampermonkey.net/index.php?browser=firefox&locale=en
https://www.tampermonkey.net/index.php?browser=opera&locale=en
https://www.tampermonkey.net/index.php?browser=edge&locale=en
https://www.tampermonkey.net/index.php?browser=safari&locale=en

2. One aspect of userscripts is that they can be easily shared by uploading to a userscript repository where they become available to other users for downloading. But if you're an internet famous person, you can freely share it from your own site too.
Here you can see some popular repos https://www.tampermonkey.net/scripts.php?locale=en
After clicking to userscript downloading link Tampermonkey would load a special page for code checking / one click installing / one click updating of this userscript

3. I made an userscript for fast picking of direct links. So you would get a full list of links and paste it in your download manager. I recommend to use a "Download Master"
Summary: https://greasyfork.org/en/scripts/468205-direct-image-link-e6ai
Code: https://greasyfork.org/ru/scripts/468205-direct-image-link-e6ai/code
Click a green button on a page's top.

4. For site administration. Please set limit for "Download Master" user-agent at 10 simultaneous downloads, 30 threads, 25 mbit/s. Thanks

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Special userscripts here https://e6ai.net/forum_topics/8