After twenty years, it is unclear that the model works in its current form. The original fractional model anticipated selling planes in 1/4 fractions, rather than the 1/16 or 1/32 fractions that have emerged. Each additional partial owner creates more demand and schedule chaos for each plane, particularly during peak periods. Further, the theory that a growing customer base will reduce empty-legs has proven limited. While there have been some improvements, the best-case "floor" of empty traffic is still above twenty percent of total traffic. Worst case for new operators can approach 50 percent.