You should use SFI's system - that is a good start. But you must understand and consider cultural, demographic, economic, educational...and individual differences between people. We work with people, not with numbers!
In other words - use SFI's system as a basis, you will need to adjust to some special circumstances.
And everyone should develop their own style eventually. Start with basic rules, consider every idea, and make your own way by experience.
You should use SFI's system - that is a good start. But you must understand and consider cultural, demographic, economic, educational...and individual differences between people. We work with people, not with numbers!
In other words - use SFI's system as a basis, you will need to adjust to some special circumstances.
And everyone should develop their own style eventually. Start with basic rules, consider every idea, and make your own way by experience.