Well because in combat seconds and centimeters can make a difference. You might know it is capable of Mach 4 and can plan for that, but if it's capable of Mach

Well because in combat seconds and centimeters can make a difference. You might know it is capable of Mach 4 and can plan for that, but if it's capable of Mach 4.2 and you haven't found it economical to respond to that, it is the difference between life and death. "All warfare is based on deception" - Sun Tzu