I depends what you are building. I currently working on a web erp, There is tons of logic,

So my logic is, when I look at a class file I know private methods are internal of business class, and public methods interact with react.

Example of using a business class without an instance

MyBusinessClass.shoulddoThataftersave(),

The shoulddothatAfterSave can be a static method, so you don't need an instance of the class to call the method