As other have mentioned, IDPA is a game. The 'rules' dictate someone's concept of correct tactics for a given situation. They may or may not be correct (and much of it conflicted with my training). That said, slicing the pie is a valid method of clearing corners-which may or may not happen in a real defensive setting.

One of the major issues with the game(s) is that many of the stages are non-survivable in the real world. At least if one plays by the IDPA rules. One can learn to run the gun under pressure, which is a good thing if one doesn't get overly concerned with winning trophies.

It's your hopefully imaginary gun fight, but I'd personally rethink the 1911 platform/.45 for defensive use. I carried one for 19 years and then got issued other platforms. I've recently hauled mine out of the safe and tried burning up stored ammo. It's convinced me that there are better platforms and calibers/calibers. Short, light & crisp triggers aren't necessary for defensive use and may be hazardous to your physical and financial health. I spent 27+ years teaching people to use factory triggers, it's not a handicap (unless you have actual physical issues) to competent performance.

In the real world, shot placement is paramount. It determines your ability to neutralize the threat. Current bullet performance makes caliber moot. On the other hand, capacity (if it doesn't interfere with point one) is a very good thing.

My last serious match was a Tactical Police Competition 3 gun in 2014. While I beat a bunch of guys 30 or more years younger, I'm familiar with how you felt afterward. If you don't worry about how you placed, but how you shot and moved, it does have value.