It's certainly useful when US stations send the State in full, as most non-US citizens don't know all the abbreviations (do you know all our county abbreviations?!) . . . . some are quite obvious, like NH, FL, NY . . . but many are ambiguous. Also, I have heard a few terrible tone signals in contests . . . people get a bit upset when you give them a 596 report! And it's always been CU as far as I'm concerned . . . usually CU AGN SN .