is there a way to sort updates by when NU adds them, rather than (what i'm guessing might be) post time at whatever site the chapters are on? i've a feeling i'm gonna have a hard time wording this but here goes... there's been a few novels that just kind of show up on the NU page in time slots they obvious weren't before. like, i could refresh the page every 5 minutes for an entire day while i wait, not see the novel at all while everything else slowly scrolls by, and then i could randomly scroll down to stuff that showed up like 6 hours ago or go back a page and it's now magically there. is there a reason for this? this doesn't happen often, maybe only for like 4 or 5 novels, but it's kind of annoying when it occurs. it'd be one thing if there was a batch release and it just got pushed down or compressed, but for a release to just magically appear at some seemingly random location within the past 3 pages is a bit odd.
i've got 'em marked for my reading list, and there's a pretty sizable chunk of novels just plain gone after filtering qidian, GT, and a few other things, so there really shouldn't be an issue of "missing" the ones i actually read when they get posted, so long as they actually showed up around the top of the page where they should be.
Happens to me aswell, I believe it takes NU longer to process some releases than others, why, no idea
Which novels or what groups are translating them? Some of the releases on NU are manually approved. That means, a user manually submitted the release through their NU profile. When this happens, it requires a staff to manually approve those releases. This depends on the staff's availability. Some groups' releases could also be pushed into the manual queue by bots due to circumstances such as typo on chapter numbering. This also requires manual approval by staff, to check the release first before it goes to the homepage. Aside from that, when a big group does a great number of release for different titles, it could also be another reason the other releases can't be found on the first page. I once tried to find a NUI release from the homepage and it requires me to jump to the 6th page because of the amount of releases on that day. You can check the number of releases listed on NU through this page (https://www.novelupdates.com/release-count-stats/) if you want to know how many are listed everyday. tl;dr there are various reasons why they got pushed back.
For my experience, ascendance of a bookworm. It sometimes pops out of nowhere in my new releases. Maybe some delay when its released? I always drop in every few hours and suddenly its on the spot a few hours/minutes earlier than the ones i saw/read a while ago.
hail the king and peerless white emperor are/were the biggest ones that come to mind. pwe is the worst, as their first release'll show up 2-3 pages back. HTK's usually still on first page, albeit somewhere in the middle each time. i can kinda understand the manual approval thing, which i feel might be a big part, but it seems odd that they wouldn't just show up based on when they're approved, rather than submitted...
just like @LaDy G said, there are a lot of reasons why a release could suddenly pop out. one of those are 'caching'. some site owners turned on caching for everything, including rss. this actually hinders the bot's ability to read them 'real-time'. and when the bot finally able to read them, its already been several hours from the attached timestamp (timestamp of tl's post) time region difference sometimes are also a factor. to the submitter (of a manual submission), his time probably is still tuesday, october 2nd, hence he submit it that way,(when NU is already wednesday) peerless white emperor (by syzc), are all manually submitted. they don't have rss. and half of the times were actually submitted by readers, not the tl. more often than not, they were submitted faithful to original dates, hence, multiple pages back. i should also mention we usually pushed multiple simultaneous release ( >10 ) away from front page, keeping only 3-5 displayed at the front, and peerless white emperor usually are in a bundle of more than a dozen.
if its new, for example Hundred, where the tl is actually alternating releases between later volumes and earlier volumes, we usually let it be for a few days (often more). once it has cooled down, we'll re-sort it. if its between multiple translators, for example: qi vs ww, we might let it sit even longer, only periodically re-sort them. (due to their high release rate). in some cases, we might not be able to at all, due to difference in numbering approach. (HJC as an example)