There is no bulletproof plan as such. Be it with business or personal life. What most of us do is optimize for adversity. Keep a plan B; I have been asked and advised.
I don’t know much about others, but I have lived a wholesome life, the best of both worlds. I don’t believe in these multiple plans as it gives an excuse to fail and perish.
I am a big believer in focus and doing one thing at a time. So this paranoia of multi-tasking, biohacking makes me go nuts.
Sometimes the best way to live a life is to have no plans but to live in the moment.