private Cell mergeIn(Cell other) {
      return mergeIn(other, 1);
    }
Returns average raw (not gzipped) tile size in this aggregation, weighted by the {@link TileWeights} instance
provided.

@see #weightedAverageArchivedSize()
planetiler-core/src/main/java/com/onthegomap/planetiler/util/TilesetSummaryStatistics.java