I thought I'd seen every type of marital arrangement until I met some friends of my parents this weekend who pay for everything separately - including their restaurant meals. They are happily married but keep their own accounts and asked for separate bills when we went out for lunch. My in laws are similar: they divide up which of them pays the mortgage, the utilities, etc so that it is even between them.
By contrast, my wife and I pool all of our earnings and pay all of our bills out of one account.
How do most couples do this?