[Grizzly]

I've done relays of varying lengths and captained a team on the Banff-Calgary road race.<br><br>
Speaking from personal experience, I'd say "both". Train for longer distances (stamina), and do doubles. But I don't see the value in stressing your body out with the couple of hour break, that's for race day. Do am and pm runs.<br><br>
If your legs are 5 miles each, think of a 13-15 mile run in your training plan once or twice. Get some good base up and you'll be fine.

 

[Grizzly]

Nothing you can do now but ensure that you're well rested! Look at the race profile for your legs and figure out strategy. Can you run them all flat out? (Be realistic!) What can you do to rest/recover in between. One thing you're going to both have to be mindful of is the fact that you will need to stretch.<br><br>
Don't stretch right away, but don't leave it for the last moment either. If you're in a cramped car or van for a couple of hours you might be warm but your muscles might seize up too.<br><br>
Bring a change of running gear. If it is raining you will need it.<br><br>
Bring a hoodie or something warm to keep yourself warm in. Unless this is Floridia or something abysmally hot all year round you'll want to take the edge off, even if it is in the 60's.<br><br>
Take some protein / recovery drink in between the legs - particularly yours RBS.<br><br>
Hydrate.