Joint ownership can sometimes be like walking a tightrope. I'm quite elderly and my husband is deceased. In order to allow my assets to pass more quickly to my children, I have added their names to my bank account and the deed for my house. The most important characteristic of joint tenancy is survivorship.
Joint tenancy applies only to the particular property held that way.
A properly drawn will covers all property owned. In addition, joint tenancy does not substitute for a will because both joint tenants may die simultaneously, leaving unclear directions for disposition of property. In many cases, it does. However, if the deceased owned other property besides that held in joint tenancy, the other property must still be probated. Joint tenancy does not remove the need for a will.