Board Thread:Editing Discussions/@comment-26391060-20141108185515/@comment-6697950-20141109110238

Unless it's specifically breaks chronology, it's not an error. They cleared the 21st floor within hours of it becoming available, so I don't see why beating 2 floors in 3 days is any more abnormal than that.

And anime based chronology isn't too reliable anyway, as they have made actual chronology errors where they clearly messed up the date. The timeline page is only for chronology that doesn't conflict with the novel.