I am not currently in Sinbad campaign but I would really want to see more campaigns introducing different payrate that is not based on number of written posts.
My best experience was with signature campaigns that allow me to write in my usual style and they don't force me to write 50+ posts.
That probably makes job much easier for manager because they don't have to check every single post, but you than you can't accept anyone in campaigns like this.
I think currently Foxpup pays like this for their Avatar, and I want to see more campaigns doing this.
In case of abuse or inactivity manager should be allowed to remove participants at any time.

Just my 2 sats