@Moesakuara
Cheers! I tend to mostly use square panels because it's simple, but by no means do you have to. There are a couple in there so far where the panels are tilted, mostly in action shots, because it adds energy the same way it does on a page! I should also note, I had... really, no clue what I was doing in the early episodes. I intend to redo them, probably up to the point where my scruffy dude leaves the cockpit. I start getting the hang of things a bit more from that point.
I'm still learning, and the next two upcoming episodes are where I start to really get a handle of what the format can do. Which... isn't much help right now, understandably, but I can point you to a couple of amazing comics which truly show off what a vertical format can do.
This creator actually works primarily in page format, but she storyboards for both, to ensure the pacing and layout works across formats. She does gorgeous things with panel borders.
This comic is 100% made for scroll, and it's what compelled me to finally make the switch. It's absolutely stunning.
@Caro
There will always be exceptions to the norm, I'm not denying that. Your experience is proof! And there's definitely a huge and growing market for physical graphic novels, especially in kidlit; those were initially what I wanted to make. That market is getting stronger with each passing year.
I'm just observing general trends. For new webcomics, the easiest place to find readers and develop an audience is on WEBTOON. The preference there is for the vertical format. If a new author is looking for the smoothest path to gaining a solid readership, that's the way to go. It doesn't mean you can't, or shouldn't, take another path. Just that growth will probably be slower. That's an acceptable trade for many people, but it's wise to be aware of the choice being made.
I really regret starting my comic in page format. I shot myself in the foot in those critical early months, where a 'rising stars' feature was still possible, because of my format decision. Not that such things are ever guaranteed, but I feel like my comic would have been in with a good shot had I chosen to follow the standard. I didn't, and I regret it now.