Companies use radical strategies rarely - usually only when changes in their environment render their current business models obsolete or when they voluntarily choose to embrace a new business model. The root cause and rarity of radical strategies explains their low rate of success. First, having to replace an obsolete business model is inherently risky. Second, the rarity of use means that most companies and executives have little experience of devising and implementing radical strategies. After all, many business models work successfully for decades. For example, IBM's mainframe computer business model worked from the mid-1960s to the PC revolution of the mid-1980s (Yip, 2004).