Lady Bird Johnson once said, "I wouldn't have a joint checking account with the Archangel Gabriel."
Having had them in the past, and having separate finances now, I agree with her. Of course, I'm not married.
I think couples should have at least three accounts, his, hers, and ours. Even if most of the money goes into the "ours," each person needs some amount of money that is theirs alone that they can spend without explanation or justification. This could range from $10 per week to <$10,000 per week depending on overall finances. JMHO.
