At what age should you stop focusing on growth and start focusing on income?

I've always heard that you should inverse your age with 100 to determine equities to bonds ratio. For example, if I'm 30 I should have 70% equities 30% bonds. But this never sat well with me. Because when I'm 50 I'm still 15 years from retirement and a 50/50 portfolio seems really weak on growth.

So, what is the rule? Do you stay 80/20 or 90/10 until like 5 years from retirement or switch at a certain age?

When should you be primarily bonds or value etds with dividends ?