Like the others said, it depends! Part of it depends on the pacing of your comic. I do think having some kind of regular schedule is helpful -- whether that's 3x a week, weekly, every-first-of-the-month, or whatever.
If you have, for example, one page where a character approaches a building and sees a large door, the next page they push the door open and peek inside, and the next page they peer down a vast hallway.... if all those pages go up at once, it's a nice, atmospheric moment. But if that's updating with one page a week, then it feels suuuuuuuper slow... it's taken almost a month just to open a door! And the page of, say, peeking inside kind of loses its tension when it's all by itself.
But if you do have the kind of pacing where there's something interesting happening on each page -- even if that's just an interesting character interaction -- then updating page by page so you can update more often has advantages too! You'll get more eyes on your comic and be able to grow your audience more quickly. And some readers find it easier to remember what's going on when they're getting regular updates.
As a reader, I usually would prefer to get more frequent updates rather than a bunch of pages all at once, but exactly how often that should be depends partially on how long pages take you to make, and many pages should go up at once depends on how fast-paced or slow-paced your comic is.
