I hate people who use complex terminology. I hate them with fervor. But I'm going to commit the sin of creating yet another new definition just to describe the two macro-categories I use for web novels. This is done in the spirit of saving me time. Please, feel free to just use a periphrasis instead of these two hideous terms when referring to the articles.
Mercurial
That's a novel like Paranoid Mage or Primal Hunter. These novels are quick in establishing success. They burn bright from the start. Another more recent example is Double Blind.
The simplest way to think of a Mercurial Novel is in the way it starts strongly without the need for a super-lengthy background. And in the webnovelistic world, where length is dilated, I'd say that means anywhere between 10-30k words. But it's hard to give a proper measure.
One of the great risks of these web novels is degrading with time. Starting strong in the webnovelistic world is terribly dangerous. There's not enough time to be smart all the time, to be planning out each move. And if you can't go back and uphold the standards, you risk chipping away at your novel's quality.
Why 'Mercurial'? Well, first of all I wanted to avoid using the famous 'Apollonian and Dionysian' duality. My classical education, sadly mixed with Christian principles instilled in me by my upbringing, brought me to see 'Dionysian' as something with a negative connotation. And the 'chaotic and randomic' nature of Dionysian might have been perceived in the wrong way. Instead, Hermes, or Mercury in the Roman tradition, is quick and a more 'positive' figure. There's nothing wrong with being Mercurial, here. Please, do not read it with the Americanized conception of 'Mercurial' as in 'erratic' or 'volatile.' The best word I can think of is 'swift.' I hope that those who don't know the Apollonian and Dionysian thing will still understand. Just replace 'swift' with 'Mercurial' and it should be clear enough.
Apollonian
Apollo is the God of prophecy, among other things. He's the God of beauty of poetry. He's not as practical, swift and crafty as Mercury/Hermes. Not even close. But he's still as important. If not more important. But that's up to others to decide. I'm extremely biased in my judgment and I prefer Apollonian novels. I don't mind Mercurial ones and I enjoyed some of them greatly. In the end, there's not one better than the other, just perception.
An Apollonian novel is longer, sometimes lighter at the beginning. The best example I can think of is The Wandering Inn. That's a lengthy novel that has many seasons in it. I'd even argue that The Wandering Inn actually starts as more Mercurial before settling on a more Apollonian pace later on. And you can exemplify the Apollonian in something that starts from slice-of-life settings and slowly transitions into heavier matters. To make a slightly incorrect comparison that might titillate some Ancient Literature students and academics, maybe Sophocles is more Mercurial while Euripides is more Apollonian, in this distinction; but again, that's more conceptual than applicable in practice.
Casual Heroing definitely belongs in this category. [For those who don't know, that's my novel.]
An Apollonian novel, in my opinion, transubstantiate from autumn to spring, while a Mercurial one stays in Summer all the time. That's a more modern comparison. Also, a bit cringy. But whatever.