The underlying problem is the size of the torrent. Maybe there should be a limit on the size of multi-file torrents. Huge torrents cause all sorts of problems and inconveniences and are not worth the slight convenience compared to a series of torrents of similar files that would otherwise be in a large collection. I have even seen torrents composed of different quality versions of the same exact video and wondered how many people downloaded all of the files because they didn't bother to check to see exactly what was in the torrent.
Complete speculation, but one reason this may be happening is that the original uploader sees that data more than equivalent to the size of the torrent has been downloaded by others and assumes that the group of downloaders has downloaded the entire torrent when they only have various partial files that don't add up to the whole.
It could also be that the original uploader of that particular collection you used as an example only seeds on the weekend or is on vacation. It is labelled as volume #4 in a series but only the original collection and volume #2 are currently available on this site. Seems like he simply adds new files to the old collection and then makes a new torrent out of the folder so volume #4 contains all of the files in volume #2 which in turn contains all of the files in the original collection. The same photos and description were used for all three collections.
https://www.gaytorrent.ru/browse.php?search=fantastic+jizzers&incldead=1&orderby=added&sort=desc
A much better solution for downloaders would have been to upload torrents of collections of only the new files instead of adding them to the previous collection and creating a new torrent out of the entire, growing folder.
It's not a real solution, but a way for you to avoid a bunch of partial files would be to choose to download only a few of the files in a large collection at a time so that they will (hopefully) be complete even if the uploader stops seeding prematurely.