Use a prep service. Any of the decent ones will take your stories and help you polish them up, not give you canned things to say.
This interview is too important to go into without having every card up your sleeve that you can.
A year minimum between callbacks will put you 500+ down the seniority list if things continue like they have recently. That’s huge and too much to gamble.
Spend the money. Do the prep. Kill the interview.