Those are not all weekly
With all due respect... are you anal retentive?
That is very close to weekly, with the occasional release taking an extra day or two or an extra week. That's a really good, steady rate right there, not one that you could say is only monthly.... there is never a full month between any of those dates.
Many series cannot say the same. Most series cannot claim the same.
what does hiatsu mean?
Do you mean hiatus? A hiatus is a break from work. With an anime/manga it could be that the author needs a little extra time to prepare the chapter or something happened to the author or to the series that is preventing it from being worked on. Could be a broken wrist or a legal issue, or any other reason.
D.Gray-man had some rather long ones ^^;