It matters because coming from the west coast, I often get stuck with 0600L flights on my day off (with a connection) to get to CVG with enough time to get legal rest. If I jumpseat on the system, I sleep in at home, take a leisurely 1830L departure, get to the sort about 3 hours before departure, then work a leg outbound. Plus, like CandlerKid says, you don't get imputed.

It's safer to take the late departure, too. I'm way less tired on that outbound operating leg if I sleep in at home on my last day off.