Are they? There's something I want to bring up. I feel like TOCs are less and less important for determine the success of a series and my interest in them has greatly declined the past year. I wonder what changed in the ranking system but it doesn't feel accurate anymore. Sales seems to be a better measure now. What do you think?
If at least they released the number of digital sales....
I always felt as if sales were more important. The way I see things, TOC is an indicator of what Shueisha wants to promote that week. This matters more for new series, since usually, if Shueisha wants to promote them more, that that should mean it's doing well with readers. However, if you're more established, the rankings don't matter as you already have an established audience that will read your series no matter where it's placed. To compound upon this, rankings are relative, and considering there's no many newbies out, it's possible that a series could rank high - mostly because it's simply doing better than other newbies.
However, Shueisha can promote things as much as they want. If what they promote isn't selling, then it ultimately doesn't matter. Cause it's not making money, and the volume sales are where the real profits can be made. Again, I bring up Samurai 8. Shueisha promoted it heavily, ESPECIALLY when the first two volumes released, but it didn't sell. So it was axed in 5.