public void updateAsScheduled(int numUpdates) {
    super.updateAsScheduled(numUpdates) ;
    updateLandingStrip() ;
    if (! structure.intact()) return ;
    
    final Batch <Venue> depots = Deliveries.nearbyDepots(this, world) ;
    for (Service type : ALL_COMMODITIES) {
      final int level = exportLevel(type) ;
      if (level > 0) stocks.forceDemand(
        type, level, VenueStocks.TIER_CONSUMER
      ) ;
      if (level < 0) stocks.forceDemand(
        type, 0 - level, VenueStocks.TIER_PRODUCER
      ) ;
      stocks.diffuseDemand(type, depots) ;
      stocks.diffuseDemand(type) ;
    }
  }