Does anyone know of a webcomic that updates monthly with chapters?
Or possibly weekly like manga in shonen jump and such?

And do you think that it's a good way to update a webcomic?

Hmm, I used to know one called 'Wish3' that did that, but I haven't read it in a while. Problem is that though theoretically updating in chunks is superior to updating one page at a time when you're making a story comic, people tend to forget about your comic, or interest dies off if you don't update regularly on the web. Put simply, you could pull it off if your comic was really great and you updated on time with a nice big number of pages like a monthly comic, but for most of us, daily, weekly or whatever is easier. A few more comics DO manage to do updates just every week or two of a handful of pages, it seems to work quite well.
Personally I don't always have as much time for comicking as I'd like, and when I finish a page, I like to put it up as soon as I can. I have done a 3 page update once, but it didn't really appeal to me, it felt like more work for less attention. People give you the same amount of attention for one page (6 hours work) as they do for 3 pages in one update (18 hours work), so I actually get more feedback and new readers from doing things one page at a time!
Of course, updating in chunks has advantages, the readers are less likely to get lost, and pages don't have to be stand-alone works of art. When updating in single pages, people expect every page to be perfect and special, because they linger over the page. When there's plenty of story to get through, they pay less attention, so you can get away with less detail and the odd mistake more easily.
In the end, it's up to you, I guess.

Back when I was just reading webcomics I use to wish they updated like that. I like reading and can fly through books pretty fast so if I'm really into a story one to three pages a week is torture for me.

However, now that I actually do a webcomic I can see how its hard. The key thing about most webcomics is that its something most people do on the side. Everyone has school, jobs, and lives beyond it so actually sitting down and doing enough work to actually be able to do huge updates quickly enough and often enough to keep readership is difficult. If you were in a position where it was possible then I would say to give it a try if you really wanted to. Personally though I've never read one that was updated like that and I can't even imagine trying to do it myself.

DRose
Back when I was just reading webcomics I use to wish they updated like that. I like reading and can fly through books pretty fast so if I'm really into a story one to three pages a week is torture for me.

However, now that I actually do a webcomic I can see how its hard. The key thing about most webcomics is that its something most people do on the side. Everyone has school, jobs, and lives beyond it so actually sitting down and doing enough work to actually be able to do huge updates quickly enough and often enough to keep readership is difficult. If you were in a position where it was possible then I would say to give it a try if you really wanted to. Personally though I've never read one that was updated like that and I can't even imagine trying to do it myself.

Yeah. I definitly see how hard that would be for me to do.

first couple chapters of my planet closest to heaven comic I updated in chunks one chapter per month... then the chapters started getting longer and I couldn't do it anymore.

It depends on the content. If the comic were a gag strip then one page updates would definately be better, though if it were a serious story, it'd be way better to be updated in chunks.