What's the longest a complete flop in both ranks and sales has survived before? Spring Weapon got enough okay ranks to not be considered a flop but I guess Japan/David maybe could count?
Usually a series making it past ch 20 means it was at least popular enough to survive one round, but Saiyuuki is getting so much extra time without needing to do that, especially for a mangaka without a previous hit. I mean it's nice that the guy's getting enough time to tell a proper full story arc and write a real ending after Mutou Black ending in just 12 chapters but still, it's odd.
I suppose it did get a good first rank even if the rest and the sales have been bad? Series with a good ranking first couple chapters do tend to make it to the 20s often I suppose, so maybe that's why it's still around (could just be pure luck though due to when batches were planned, or editor favouritism like with Spring Weapon).