How Long Did it Take to Burn In a new piece?

What was the longest time period you ever had to go through when burning/breaking in a new piece of equipment,regardless if was electronics,power cords,speakers,wires,etc.,untill it finally was broken-in and showed its true colors? Would you fellow GON members be willing to share what equipment/timespan you went through this with,and was the transformation gradual or a sudden snap at a specific time? Also,were their certain pieces that never "blossomed" and lived up to your expectations after a lengthy burn-in period,so off they went after your hard work waiting for them to reach their potential.