Personally, I think "blank canvas" is perfect for newbies who might benefit from exposure to experience a breadth of activities before they rule anything out. That happened to me, and had it been more narrow, I would have really missed out.

I also think it's superb for non-newbies - especially when you already have a relationship or strong sense of who the domme is. There are only two dommes who I could comfortably tell "Have your way. You know me, and I trust you." And that is truly a special relationship.

So, I defintely see value in open-ended sessions, and I'm sure (from experience) that this can be a great approach.