What kind of lines do you want to build? If the optimizer builds pairings with short layovers and long duty days that can't turn to another trip--that would be easy because you'd have a day off in between all your trips. Building commutable lines using some of these optimized pairings is a challenge.

I think we saw a lot of system delays this winter because of crews going illegal on some of these optimized pairings. I've had multiple 8 in 24 problems this winter that I've never had before. People pay for a premium product at FedEx and when the screws are too tight and cause problems, the customers will go elsewhere.