That's what seasoned writers tell you. I both agree and disagree.
If writing is your profession, then you have to take it seriously — there's no way around that. I know how to be disciplined, and even though I spent roughly a year on both my first and second books, I wasn't writing the entire year.
When you're a beginning writer, it's hard to squeeze out pages every single day. Because once you finish your first book, you discover a whole front of work that was invisible before. There's no publishing house waiting impatiently for your new manuscript, hounding you to finish it like in the movies. You don't have a name that gets publishers lining up with their best offers. You realize that turning the dream of being a popular writer — sitting at a big oak desk by a window with a rose bush peeking in and the curtains billowing in the breeze, your agent calling to hurry you along — into reality means you have to work. As an editor, a proofreader, a layout designer, an agent, your own assistant, a marketer, and God knows what else. For who knows how many years.
So once a newly minted writer finishes a book, they start doing an entirely different kind of work. Whereas an experienced writer has already walked that road, and their job now is simply to write and write. Every day, no fewer pages than whatever quota they've set for themselves.
I did the same — writing 2,000 characters a day. More was fine, but never less. But once the promotional work started piling up, I had to set the new book aside. When I finished with that part of the work, I got back to writing.
There was also a stretch once when I just couldn't write. Whatever I tried, I couldn't squeeze out a single line. I was that burned out on the whole thing.
Still, inspiration is real. I do have to wait for it sometimes. I simply can't force myself, no matter what famous writers say. In the end, you have to work from where you actually are — your own wants, your own capacity.
I'm not complaining. I'm just telling it like it is. As for you — do whatever works, whatever's comfortable for you, because who knows better than you what's best for you?