code: def _get_timethresh_heuristics(self):
          
          if self.length > 1E5:
              time_thresh = 2.5
          elif self.length > 1E4:
              time_thresh = 2.0
          elif self.length > 1E3:
              time_thresh = 1.0
          else:
              time_thresh = 0.5
          return time_thresh
docs: resonably decent hueristics for how much time to wait before
          updating progress.