It does indeed seem to be a numbers game.

I totally understand what you are saying re: blasts and may end up insisting next time. I know that in NYC they only want to use blasts regardless of how many (I'm an expat who married an Aussie, thus I know way more about US practices from my friends over there than I do about this process here.

My latest "concern" (I worry about everything!), if you can call it that, is about the quality of the labs. My understanding is that the reason why blasts are sometimes not the first choice is that they have to be transferred to a new culture. Thus, it sounds to me that both the skill of the lab technicians and the quality of the lab are significant factors. Of course, the quality of the embryo is at least equally important, but I do wonder how much also comes down to the lab. and I do not know how to find out about this.