It's even better due to the way percentages work - if you undercrank by 10% you get a bit over 11% more time (after 100% of the original time, you still have 10

It's even better due to the way percentages work - if you undercrank by 10% you get a bit over 11% more time (after 100% of the original time, you still have 10% of the reel left, but you keep undercranking, so by the end of the 10% extra time, you still have 1% of the reel left, etc.).