Retirement corpus planning is as vague as it gets and it would keep changing with your goals and changing.
Your retirement goals should be to experience things you want to including traveling, food and create memories while saving money that you can.
Its important to save for the future but enjoy your present and life.
We think so much of retirement but ask someone with near death experience or is critically ill about their regrets and money would be the last thing on their mind.
De-stress, enjoy, be happy and make memories before the body gives in and you have all the money and time but can't eat this or that or can't travel due to health issues or maybe you lose interest in things you have planned to do after retirement.
Just think about things to do before I die and try making them happen while you also save some money :)