It isn't up to Part 8. I'll assume that you meant Part 7, though.
Part 7 (Steel Ball Run) WAS weekly for the first 44 chapters, but then Araki decided to switch magazines, and went from Weekly Shonen Jump, a weekly shonen magazine (as is evident from the title) to Monthly Ultra Jump, a monthly seinen magazine. It's had about 70 chapters in Ultra Jump, in addition to the 44 in Weekly Jump, but the numbering of the Ultra Jump chapters started from 1 again. Part 7 is still ongoing, though I believe that it's near the end. I'm not sure how near the end, since the scanlations are only up to volume 9, and I don't read the spoiler bits that come out each month. I think it's maybe a year or so away from the end, so that's about 3 or 4 volumes' worth.