Alan,
depends on the situation, the room I'm shooting in and what I'm trying to do with the images. For show formals in a large space with black dogs (I do a lot of Rottie shows), I always use two strobes but only the primary (on the "eye" side) provides a catch light while the other is to light the body. In the studio, I usually use two strobes and like the two catch-light look for people, primarily. But when space is tight and I have lots of puppy wranglers as I did for these photos, the less equipment in the way the better. I used one strobe with a PLM and since some of the final images simulate outdoors, the single catchlight is more realistic.

Jim