What is the 50 30 20 rule when selling?

Excuse me, could you please clarify what the 50 30 20 rule refers to in the context of selling? Is it a strategy or a principle that guides the allocation of resources when selling assets, such as cryptocurrencies or other financial instruments? I'm curious to understand how this rule works and what its key components are, specifically the 50%, 30%, and 20% breakdowns. Additionally, I'd like to know if this rule is widely accepted or recommended in the world of finance and cryptocurrency trading.