To add to this, and reiterate as the other users have, Chapters should an indication if a new posted chapter is skipping the last posted chapter by any number greater than or equal to 2, in both the following and the regular manga page.
I don't know exactly how the infrastructure or categorizing on this website is designed, but it shouldn't be too unreasonable to add a simple integer check into the process of when a chapter is uploaded. There is a field that takes into account the Chapter Number. The tag should occur in such a scenario, comparing Ch.46 (the chapter being uploaded) to Ch.12 (the most recent up-to-date chapter) would trigger a tag, but not when comparing any of the following:
[ul]Ch.45 & Ch.44
Ch.45.1 & Ch.44.
Ch.12 & Ch.44[/ul]
To hijack this post a bit, if possible, since it's a similar endeavor that stems from the same issue, there should also be a check to see if an upload is a re-upload and mark it as such. If Ch.44 is posted and another chapter has already been uploaded with the integer 44 in the Chapter Number section, the newest upload should be subsequently be marked with a "Re-upload" tag, just as we have an "end" tag.
Simply put, just as we see an "end" tag on a chapter in the following/manga page list, we should have some sort of indication if a chapter is an irregularity: skipped chapters or a re-upload.
As for why these changes should be implemented, some translators / groups are intentionally assholes.
Hatsukoi Zombie recently had the last chapter spoiled by a user who uploaded the last chapter after another group has already put in a great deal of work into the series. Said user has done this before, and clearly does it maliciously as per his words in the comment sections. Sniping a series is one thing, but uploading the last chapter of a series after another group has already done the bulk of the work, and skipping several chapters in the process to spite and spoil users is on a whole other level. It's not like the series wasn't getting regular updates or the user cranked out the last few chapters because the uploads were too slow, he intentionally skipped chapters, sniped the last chapter, and intentionally spoiled some number of users.
Another example is multiple groups have intentionally posted re-uploads several weeks to months behind, often in retaliation to another group picking up a series they felt they "owned". I've seen multiple series not receive uploads from anywhere between 1 to 3+ months at a time from the group who was most recently translating it, and then have said series be picked up by another group. Shortly after a new group has picked up a series, the previously group will run back to the series, like a child fighting over a toy they had discarded at a daycare and wanted back once they saw another child playing with it, and try to claim some sort of ownership over the series. Usually with excuses of being delayed, the new group should have asked permission, etc. If a re-upload filter is implemented, this could be a non-issue, but it's still irritating and somewhat of a problem seeing a group try and fight another group over a series they neglected by trying to lay claims of ownership over the series or complain about not being contacted or such. Especially when it ends with the new group leaving and the old group neglecting the series again after a few chapters.
I think the administrators should genuinely consider adding rules in regards to spoiler chapters and maybe even certain re-uploads. There are rules against spoiling in the comment section, there should be rules against uploading chapters way ahead of the last translated chapter. Not everyone is going to notice until it's they've already read half the chapter. Groups being passive or overtly aggressive dickheads and re-uploading chapters because they feel a series was poached when they haven't uploaded in 2 or 3 months should also be deliberated. It's one thing to have a race between groups as we had on Kishuku Gakkou no Juliet, or a re-upload that has a serious jump in quality; redrawing sound effects or text in panels instead of text bubbles, or significantly higher quality scans, but re-uploads of worse or equal quality, with largely analogous grammar / wording, that are done out of spite or a narcissistic sense of ownership, especially if there are no plans to implement a re-upload tag, is an issue that Admins should consider implementing rules against.