The figures in the paper you linked below are log_10 scale on one axis but not the other. Thus even without quite understanding what all these figures measure,

The figures in the paper you linked below are log_10 scale on one axis but not the other. Thus even without quite understanding what all these figures measure, it seems to me that answer the question about "linear growth" is a hard no: double the size will not be twice as good. Or am I misunderstanding how to read these graphs?