As noted by others there are two ways of looking at this.
1. You’re losing out
2. You still have the chance of getting a player on 19 casinos if he / she happened to sign up on one
Tough one this.
To me cross promoting at the other groups makes sense – they have at most 7 or so brands. When there are twenty brands maybe I want the chance of landing a player. The number of casinos does make a difference IMHO.
Not saying it’s right, but think about it.