Different timeouts mean different things. When you're working on the client.. you're probably looking mostly at the SendTimeout - check this reference - wonderful and relevant explanation: http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/84551e45-19a2-4d0d-bcc0-516a4041943d/
It says:
Brief summary of binding timeout knobs...
Client side:
SendTimeout is used to initialize the OperationTimeout, which governs the whole interaction for sending a message (including receiving a reply message in a request-reply case). This timeout also applies when sending reply messages from a CallbackContract method.
OpenTimeout and CloseTimeout are used when opening and closing channels (when no explicit timeout value is passed).
ReceiveTimeout is not used.
Server side:
Send, Open, and Close Timeout same as on client (for Callbacks).
ReceiveTimeout is used by ServiceFramework layer to initialize the session-idle timeout.