Largest change in route evaluation between regulars?

We've got a walking route that's probably 9.5 to 10 hours long going up for bid soon, after the old regular ran it in 8 hours every day until his body physically couldn't take it anymore and he quit.

And anyways, that got me thinking, what's the biggest swing anybody's ever seen between one regular bidding off the route and a new regular starting on it? I'm sure there's got to people who've seen much bigger than a 2 hour change.