What trade discount to set for B&N to carry your book?

Hello! I know the industry standard is supposedly 55%. When Barnes & Noble would carry my children’s book, I started off with 45% and had no problems. But I think two things happened. Based on an author coach’s recommendation, I reduced it to 40%, and also I had my books carried at too many stores, which made it harder to market my books at each location; then most of my children’s books became blocked from being ordered at B&N stores that wanted to order my book. Now I’m going publish my adult books on emotional healing. Should I try starting at 45% or 50% or be on the safe side and start off with 55% trade discount?