Historical clue formulations

• Isn't serious — 2019-01-13
• Routine material — 2010-08-26
• Some are practical — 2010-01-26
• Good ones are cracked — 2007-12-16
• Parts of a routine — 2007-01-14
• They might be practical — 2001-09-11
• Laughing stock? — 1998-07-04