There definitely is not a perfect solution. The thing I'd keep in mind is that it doesn't matter what the purchase timer is to the seller. It matters to the buyer. A buyer is not going to fork over millions of gil for a house if someone else can pick it up instead. Maybe 5 minutes is too short. How about 15-45 minutes? That's probably enough to deter buyers from risking a black market purchase. And short enough that those dedicated to finding vacant plots can get a house.
It isn't like SE is going to do this anyway. Just saying that they are going from one (or two) extremes to another; FCFS, 12-24 placard clicking, lottery
