I have a question regarding schematic drawing conventions:

I see two conventions used in drawing simple power supply
schematics. The first is that circuitry always flows toward
ground synbols that are at the bottom of the schematic. This
supports the 'ground is always at the bottom' philosophy.
Positive supplies are universally shown this way - no argument
here, and many negative supplies are also shown this way.

But, I've also seen negative supplies drawn with the negative
voltages toward the bottom, with the flow of the rest of the
circuitry going upward toward ground, which is actually
drawn at the top of the drawing (ground symbol is -always-
drawn correctly though, with the point down). This method
supports the 'most positive at the top, most negative at the
bottom, ground somewhere in the middle' philosophy, much like
how voltages would look on a graph, or on an oscilloscope.

Is there a preferred or proper convention? Does it really
matter? Are there standards that would answer this question?

Curious minds want to know!