When it comes to writing, the author should stick to what they are comfortable with and only push themselves to write more if they are prepared to stretch their limits.
I'm one of those authors who write 6,000 words a day, 3 chapters a day, for several months now. This isn't the most as I know there are a couple of people who pump out even more words a day.
I can speak from experience that it is extremely difficult to maintain quality standards. I have trained myself to write 1,000 words per hour so I spend 6 hours to write every day. I don't do any proofreading or editing though my English writing skills are good enough that there aren't any grammar or spelling errors. Nonetheless, if you write so much all the time, you definitely won't be able to plan out things as much.
I didn't get to this point immediately, of course. Over the course of 1,5 years since I started writing, I started with an update rate of 2,000 words a day. Then 4,000 words a day. Then 6,000 words a day. Increasing your daily writing volume is a skill that can be trained, but it requires dedication, time and a willingness to work hard to increase it. The novel also has to be able to accommodate it and the author's imagination also has to keep up with the pace.
Not every author has the time to dedicate this much effort into doing such. If they don't have the time or don't feel motivated, it's better to stick to what is sustainable to them. I have seen too many authors break because they tried and failed to push their limits when they weren't ready for it. Listening to reader feedback and responding to their demands is only useful if it benefits the authors.
Is it exhausting? Yes. But no more so than a full-time job. The earnings I've received for writing my novel this way has made it worth it for me to write in this style and at this pace. The novels that Webnovel offers are different from published books. They don't have the best quality, but they leave you coming back for more every day.
Many authors are amateurs and don't have a lot of writing experience and that reflects in their quality of their work and their update rate. If they were pros, they would have probably brought their novels to a publishing house or Amazon instead. Webnovel offers a lower barrier to entry for authors and while there are many works that are disappointing, the charm of this platform is that there is always a gem in the rough or a particular flavor that you like from the mass of novels on offer.
Ultimately, writing is a passion and the best stories are written if the author is on fire. I write a lot of words a day, but I enjoy it and that keeps me going day after day without any depression or mood swings. Authors should pay more attention to their mental and physical well being and their financial situation to decide how much they want to write. Just responding to pure user feedback is not always healthy because usually the loudest and most extreme voices are amplified in the comments and reviews.