Hi, I'd like to help you with your question.
Yes, it is normal behavior that your husband wants to be with you once a week and chooses masturbation the rest of the time.
Everyone is different in how they express themselves sexually. Some people need sex a lot, daily if possible, and others can go a long time without it. It is all about how the individual feels and not so much about what is normal.
What is important here is whether or not you feel happy with your sex life with your husband. If you are ok with your sex life, then his behavior is fine. If you are not, then it becomes important to resolve the issue so both of you are happy.
Here is a book that may help you:
Are You Normal About Sex, Love, and Relationships? by Bernice Kanner
You can find this book on Amazon.com or your local library may have it for you.
Let me know if you have more questions.
I hope this helps you,