Comment (by Samuel Cupp):

I attempted to put in some logic to check whether it should actually call SyncProlongateBoundaries. Leaving the recursion loop unchanged, I have

  std::vector<int> check_groups;
  std::set<int> tmpgroups;
  for (int g = 0; g < pre_groups.size(); g++) {
    int gi = pre_groups[g];
    for (int vi =--

Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2653/carpet-presync-triggering-syncs-for-all