As a young man I was a faithful follower of Skeeter, Elmer and the Colonel. I was adamant about that the caliber choice was the sole determining factor in the outcome of a defensive situation. Then I read Bill Jordan's book, "No Second Place Winner". As I read more by authors like him I came to realize a .22 short that hits does more to stop the fight than a dozen misses by a .45, .44 or .357. That lesson was further driven home after becoming a Marine. Marksmanship, with ANY and EVERY weapon, is key to winning the battle.
I have a backyard range and try to get a few rounds in each week. At the minimum I will walk out and empty my EDC each week before cleaning and reloading. I understand I am in a somewhat unique position to be able to do that. Not everyone has a range that accessible. No matter what your situation is practice should be your chief concern with caliber choice being secondary or even tertiary.