In assition to Casella, the blue ocean approach is used successfully by Southwest Airlines, Cirquedu Soleil, and Curves (a chain of women-only fitness centers), among others. Chan and Mauborgne argue that successfully reorienting a firm's strategic focus requires the firm to give up long-held assumptions about how business should be conducted. They caution firams to avoid benchmarking and extensive customer research because these approaches tend to create a typical "more for less" mentality that guides the strategic focus of most firms. Instead, the blue ocean approach requires to fundamentally alter their strategic. Therein lies the challenge of blue ocean thinking: It is very, very difficult for most businesses to change. Consequently, trueblue ocean approaches tend to be a rare occurrence.