there are a bunch of things i would have suggested months ago, like a vertical scrolling format and a steady updating schedule...
but my comic Preheat was featured randomly when i was in the middle of a hiatus and rocky updating schedule (posting 1 page whenever i could, sometimes once a month, sometimes more), and the comic was in regular graphic novel format, like what you find in a book. they even eventually emailed me to ask for high res art assets to make a better banner for me, that they would reuse frequently. i eventually changed to vertical and now have a steady schedule, but they found my work and were interested in it far before i did any of those things, and they didn’t even ask me to
so... i honestly don’t know if scheduling and the format matters anymore. they’re always going to prefer it, and you won’t get picked up for premium unless you’re using vertical, but maybe this will serve as good news that it’s definitely possible to get noticed either way. as long as you have good art and an interesting story, i feel like they’re going to be the most important factors to being picked up.