The number of streamlines value indicates how many lines exist between the two seed points. Increasing this number from the default value (100) can create unique visualizations but may take some time for in:Flux to render.
The number of lines present in a streamline visualization can be edited from its properties panel in the Streamline Parameters section. The below example is from the Tutorial 1 file.
Tutorial 6 - Figure 94 - red arrow indicates location for changing the number of streamlines present in the visualization
Decreasing the line width while increasing the number of streamlines was used for the figures of streamlines at the beginning of the streamlines section of this tutorial. As an example, the below figure has a line width of "1" and the number of streamlines set to "500".
Tutorial 6 - Figure 95 - red arrows indicating where to change values in a streamlines properties panel to decrease the line width while increasing the number of streamlines shown