Assuming it's like this.

Day 1 - Upper Body
Day 2 - Lower Body
Day 3 - Off
Day 4 - Upper Body
Day 5 - Lower Body

Do you or would it be wise to split this across the two days respectively or do full upper body both times? What I mean is:

Day 1 - Chest, Bi's
Day 4 - Back, Tri's, Delts (Or Delts across 1 and 4)

Lower Body would get trained equally amongst both days.