I can only speak to my experience. I was accepted for shared risk at 39, am now 40. My numbers were all "good" and our infertility was unexplained. It is secondary infertility - we have a son and got pregnant one other time on our own prior to IVF, which was a missed miscarriage at 12 weeks. That said, we have done two rounds with them and have not gotten any viable embryos, so shared risk acceptance isn't always a guarantee.