To paint a rainfall with a custom brush or drop by drop?

[emanuelepepi]

as title says. what's the best deal? a rainfall painted with a custom brush or a rainfall that is a pain in the arse (painting all the raindrops one by one) ?

[eezacque]

Do not paint all raindrops, or all hairs, or all bricks...

[InfernoKing]

Knowing the context and whether you're doing this raster or vector helps.
Daytime, nighttime, heavy rain, light drizzle?
Abstract, cartoon, photo-realistic?

If raster, usually just a scatter brush and slanted motion blur is enough. Sometimes you might add a few stray heavier drops, real quick brush strokes with thin diameter, at a slightly different angle.
Keep note that light quality changes during rain, less defined shadows, wet-slick surfaces and reflections.

If it's night time you really only need to indicate the presence of rain around light sources and reflections from the ground.

[emanuelepepi]

Thank you InfernoKing, I've already used a scatter brush (a drop repeated with jitter effect, random size and spacing on different lines), but I didn't think about the motion blur. Your suggestions will come in a handy, I'm currently digitally painting a moderate rain (not too heavy), but the motion blur can add more depth to it.

Keep note that light quality changes during rain, less defined shadows, wet-slick surfaces and reflections.

yup thought about that

the presence of rain around light sources

yup, thought about that too, but it also depends on the direction of the rain, if not parallel to/same direction of light-source. Currently it's straight upper light source (12am), while the rain comes a little more diagonal from right to left.