I have good endurance so for me its just getting the miles in and doesn't matter if I split them up. If endurance is a weakness (I don't know if it is with you?) then it makes sense to try and do longer runs in one go. If I had an eight I would do it in one go but usually have to split them once it gets to 12 - 14 (midweek - I'd never split the long weekend run).
Saying that its all about what fits. If the schedule says 8 and you just don't have the time then 2 x 4m is better than just 1 x 4m.
Carrot - they'll be pleased to have another woman on board! Jump over there and introduce yourself.
I'm doing most of my running very early now too. I figure its dark whenever I go out so would rather get it done first thing. I need to be back by 6:30 so I work back from there. Usually head out at 5:30 but sometimes 5.
This morning I could not wake up. Went out with the dog but only managed a couple of miles. 4 done tonight to make up.