Why did Brook decide on 10 years for her $100 million goal? What does she teach on setting goal timelines?

I was listening to her conversation with Ryan M. When Ryan says it doesn’t make him feel good to put a date on a goal, Brooke asks, “Does it create a sense of urgency?” He says yes, and she replies, “So your time frames must be too short.”

I don’t remember Brooke ever teaching on this before. What is her process/thinking when setting a date for a goal?