I've only seen her 1 on 1 (but I have seen her a couple of times) and I have briefly talked to her about her gangbangs (even though they're not my thing) and as per her profile, she said they can be quite variable but even if few people turn up she still usually goes ahead. I get the impression she accepts bookings for it from a lot of people and relies on the fact that many of them don't turn up.
Personally, I think you could get "lucky" with only a few turning up but on the flip side you could get unlucky and since I doubt she'd turn anyone away you might struggle to get in a look in.