What's a typical or reasonable particle count?

I am experimenting with it now, and obviously there are too many variables for there to be one answer to this question, but how many particles do shuriken systems you have worked with use?

I will specify I am usingUnity's included Particles/Alpha Blended particle shader, with texture sheet animation. I'm using this to make small smoke / gas effects, and while I like my results so far I'm having difficulty adjusting these settings with confidence.