What is the 7 percent sell rule?

Excuse me, could you elaborate on the concept of the 7 percent sell rule? I'm curious to understand its significance in the world of cryptocurrency trading and finance. Is this a rule that traders follow to manage their portfolios and minimize risks? Could you explain how it works and why it's considered important? Also, are there any specific strategies or considerations traders should keep in mind when implementing this rule? Thank you for your time and expertise.