Exactly 13 pages 
Every single chapter Playing with numbers is fun and could be Easter eggs sometimes
As per page, well depends usually 6 panels or so, sometimes more sometimes less
As a chapter (one story within an arc) it goes from 32 to 42 pages.
As an upload to tapas, it was 32 but changed it to 20 or so (so two uploads would complete a full chapter).
Too long, probably! I cap my chapters at 5,000 words maximum (and they're usually very close to that). So, for Tapas, I have to split everything in half, making an average episode somewhere between 10 and 14k characters.
I average out to get close to 20 pages. depending on the pacing it might go a little longer or shorter than that. Prologue had 28 pages while Chapter 1 only had 17 (If I made it longer I would feel like I'm just dragging it out.) While Chapter 2 is exactly 20 pages.
Once I get better and more experience my goal would be to average out 32 pages per Chapter (like an American Comics)
If each comic upload means an 'episode', then I post 6~9 pages all at a time, that's about 1/3 of a chapter.
My chapters tend to be around 27-30 pages long so I usually put five pages into one episode. That way I can publish a new episode in 7-9 days easily.
I'm writing a novel with images and I tend to be around 600 to 1.5K. It depends on the chapter! The shorter chapters I call "interludes" and have big reveals while the longer chapters push the story forward with character arcs and worldbuilding. 
I try to stay between 30-40 panels a week, including the title panel and the post episode world building/info panel I have.
Because I don't want to exhaust my buffer, most chapters of mine tend to be around 3-4 pages, 3 if they are more text heavy and have more footnotes explaining certain linguistic terms and such.
Take a look to see how I've structured it, if you're interested:
It's only around 1 page worth on here, which can be cut down to line 5-10 depending on the formatting I'm going for. On the webtoons version I would usually try to hit around 15+ panels which again isn't a lot but it's the most respectable amount I can send out at the weeks end.
I try for around 1k. Often my first chapter will be a little shorter as I try for a more dramatic punch with less exposition so the story will unfold. As a reader if a novel's first chapter goes on like my old aunt Betty prattling on and on I don't read more of it. It seems like too much filler.
All that said, however, I really favor a "natural" break. Sometimes if you've only got about 500 words but everything feels complete, then do that. We've all read something where we've paged ahead waiting for the point. And, we've all read something that was longer but was so well put together we didn't notice the length.
Write hard, write true.
I usually try to keep it at 5 to 7 panels an update, but it really depends on where a moment stops and starts. I wouldn't want the episode to end on something that feels like a cut off sentence, but I also want to leave the end of the page at a place where what happens next is interesting enough to get someone to come back. Sometimes I'll do more panels if I feel like it needs a bit more.
My shortest episode is 15 pages
my longest episode so far is 43 pages
i upload everything at once tho but on a monthly time schedule
When I started out the number of panels varied based on what kind of story I was trying to tell in that update. Recently I’ve transitioned to trying to keep as close as possible to 4 panels per update because it makes it a lot easier to format for sharing on social media. Tapas and webtoon only draw In people who are really into webcomics. Most people who read webcomics seem to encounter them through places like Instagram or Reddit. Having flexibility in my formatting so that I can post a scrollable form here and a more traditional version elsewhere has really helped increase my audience a lot.
An episode of mine that may get 25 views and 10 likes on Tapas will easily get 300-400 upvotes on Reddit for example.
TreasureHUNT!! operated on mostly page-a-week updates, so I think the average panel count was around... 5-6 probably?
The comic I'm working on now... it's kinda too early to tell lol. It's vertical scroll format, but the length also fluctuates a lot based on the episode content. Like, the premise is that it's a slice of life based on a D&D campaign I'm currently playing, so some episodes are pretty quick if it's just telling a single joke or scene, but some are more plot heavy and thus lend themselves to longer strips.
I think the shortest so far is like 12 and the longest is 36? So maybe average of 20 panels? xD
Mine are getting longer and longer. 
But that's because I'm trying not to drown my panels in dialogue these days. 
Way too long, man. They average 10-12 full comic pages, which makes about 32 images to upload to Tapas. Mine are way too long for Tapas, and I need to cut that in half. 
For me it was more about making one complete thought than trying to fit in a cap. For long form it can be anywhere between 10 and 40+ panels. But, for my page format one, I just did one page a week. On Webtoon however-- for that same comic I upload those pages 5-6 pages at a time per episode. So I think Webtoon likes longer episodes and will wait much longer for them. Tapas, they're cool with short snippets if they get more updates more often.
Overall, it's just...however long it takes to say a thing I need for that update.