Looking at a lot of the webtoons that they have that are featured, I think the ones that have more detail were already really famous, so they were probably able to negotiate better contracts to match their output. Or, they were able to hire assistants with money from patreon donations as well, but people who are new authors that are featured tend to do webtoons that are a lot simpler in style, probably simpler than their normal illustrations.
Like, if you're looking to get featured, it's way more likely that you're going to approach webtoon than webtoon approaching you, which means you'd already be approaching them with a comic that has a simple style you could potentially do for the long term. So there wouldn't really be a need to worry about the style getting in the way. Something like Villains (https://tapas.io/series/villains ) which is a Tapas featured comic, but I think did a really good job of having a lot of panels in their updates, but they've done a style that is simple, clean, has a lot of closeups so they don't have to worry about like...backgrounds--it's something you could look at and say "ah yes, they can do 40 panels a week. They've figured it out."
But as for the hard core painterly comics, which I love--I think Webtoon is aware it's not physically possible.