Ahhh...I'm pretty new to all this, so I'm not sure if this is what you're looking for, so...ignore me if I'm missing your question. =D
Consider a four-dealer layout: 3 1 4 2
If you had a greedy that strictly tried to make 1 happy, then 2, then 3, then 4, your program would function like this...
3 1 4 2
Make 1 happy...
1 3 4 2
Wait a day, then make 2 happy...
1 2 4 3
Wait a day, then make 3 and 4 happy...
1 2 3 4
So your program would claim that it would take three days (unless I'm misinterpreting what you mean, which is very possible).
But the real solution does this:
3 1 4 2
Make 1 and 4 happy on the first day (the transactions do not overlap).
1 3 2 4
Make 2 and 3 happy.
1 2 3 4
So the real solution takes only two days.
Still, not sure if greedy works even after taking that into account--I haven't attempted that problem yet.