There are a few disadvantages to the way you're doing it.
1 is that, on Tapas at least, there is no mid-episode bookmark system so folks have to sit down and read through the whole thing in one go, lest they lose their place if they go away and come back to read halfway through an issue. This isn't a problem for everyone, but some folks are used to shorter uploads on this site and may be overwhelmed by episodes that are that long. Further, if you're editing episodes onto the end, readers will get sent to the top of the episode every time they click to see a new page and have to scroll all the way down to continue to the new page. Webtoons has a bookmark feature which somewhat alleviates this, although I'm not sure how it interacts with episodes that have content added after the fact.
The other big issue is how notifications work on Tapas. When you upload a new episode, it shows up as a "bookmark" notification, where as when you edit an episode it shows up as a "bell" notification. Only bookmark type notifications bump your series to the top of "Fresh" (for visibility), and also not all readers pay attention to the bell notifications for series, because usually an "edit/update" is for minor fixes like spelling or art or wev. Further I haven't used the app in a while (just checked, apparently my phone is too old to be compatible now. RIP) but it used to be that app readers didn't get the bell notifications at all. So folks who primarily read that way would just have... no way to know that the series was updating.
A few years ago there was a thread about this, where a user was puzzled as to why their comic was getting so little interaction and growth. It turned out that a somewhat significant reason why was because they were doing their chapters like this. It was just completely killing the series' visibility to new readers, and also not communicating properly to the existing readers what was happening/when updates would go up.
In short, the length may or may not be an issue depending on your audience's preferences, but I would absolutely avoid updating new pages into an existing episode like that. If you want to post in bulk, wait until the bulk is done.