Historical clue formulations

• Big ask ... or a hint to this puzzle's shaded squares? — 2025-07-22
• Hard thing to pull off — 2009-10-10
• Challenge — 2009-02-08
• That's a lot to do — 2007-06-17
• Really big job — 2006-03-04
• Hard-to-meet requirement — 2004-10-08
• Hard thing to fill — 2004-05-08
• Tough request — 2003-11-08
• Tough thing to fill — 2003-10-10
• Challenge — 2000-11-18
• Lot to ask — 1999-02-20