According to the FET calendar (which is presumably taken from... one of the fanbooks?) the Nationals spans only three days, with rounds 1, 2, and the quarterfinal matches all on the first day, the re-scheduled quarterfinals for Seigaku vs. Hyotei on the second day (after the rain suspension thing), the semi-finals on the second day, and the finals on the third day. That seems... impossibly speedy, so I don't know if that's FET's estimate or Konomi's final word on the matter. :-??