While I am hyper-obsessive and practically need my manga spoon-feeded to me constantly, on realistic terms I'd be willing to wait a month or more. It's fun reading the pieces in the weekly magazines, but I noticed that sometimes the artists are so rushed that their art looks as such. I can only imagine what the weekly authors could produce if they had more time (by judging how wonderful their "rushed" art is). I love manga that's drawn with care, so to me, if it takes more than a month to draw a great chapter or two, I'm definitely up for waiting.
I'd rather read a story in long blocks -- or better yet, all at once. But I understand that it's usually more expedient to update a manga series in weekly/monthly increments. So my vote's for monthly. I don't mind waiting for extra pages and better story flow.