But they may be surprised to learn that the rule’s creator, Bill Bengen, never intended it to be a baseline for retirement income planning. “I never intended it to be a panacea for ‘safe’ retirement income planning, but that’s kind of what it’s become,” Bengen said. “It’s potentially more appealing in practice because most Americans are comfortable taking some risk with their retirement income plan and making adjustments along the way.” He’s ready to take on Warren Buffett’s retirement income advice. “That approach makes sense on first look, but you have to test every idea thoroughly when it comes to retirement income planning,” Bengen said.