All of the CMS I've tried doesn't clean-up well with their temporary attachments. For example, when I write an article and uploaded a bunch of images but then I lost my internet connection and my IP has changed, I have to refresh the page again to submit. Refreshing it will leave the previously unused attached images in its directory.
Or a simple scenario where I write an article, attach images and then decided to go back to the articles list without finishing it. This will result to a lot of unused images/attachments that will reside in the upload directory.
It's manageable if you're only the author because you know what and where are the junk attachments. It becomes unmanageable and problematic if you have multiple authors.
This doesn't seem to be the behavior of XF. When I create a new thread, upload files but then decided to go back to the forums list, I found out that XF silently delete those junk, temporary files. This is really a great feature especially in forum where your members are all authors of content.
Thumbs Up for this unseen HYS & unadvertised feature