Safe rules typically ask for unambiguous contexts, therefore rule batches need to be repeated so less heuristic rules can be retried once their context has become a little less ambiguous due to other rules.
for the 6 heuristicity levels in the morphological disambiguation CG, batch order will be 1 -2 -1 -2 -3 -1 -2 -3 -4 -1 -2 -3 -4 -5 -1 -2 -3 -4 -5 -6 -1 -2 -3 -4 -5 -6, with 1 being the safest and 6 the most heuristic level.