24 hours, peaked, full mile outdoors. Perfect weather, no wind, sea level. Has something mechanical like a pace car to pace him in exact even splits, and has a huge crowd watching him to hype him up. Has good fueling in between.
Additionally, what would have been the optimal way to space them out? 1-4 hours in between? I bet someone will say Daniel Komen spacing and run them back to back.
I say he could have run 5-6 with a possible seventh depending on how long a day he wanted and how badly he needed sleep. Has about 2 hours each in between since he likely does not need 4-ish hours to recover and he would not be running sub 4 after being awake almost 24 hours on tired legs.