This brief description of my day is just like a fight, except in your typical fight everything is compressed into a few seconds. "Fighting," as Scott Reitz says, "is problem solving at high speeds." You're presented a problem, and you have to come up with a solution for that problem and apply it immediately.
When you have a base of skill that you can consistently apply effectively at high speeds your problem solving ability improves tremendously. I recall shooting with a police officer who struggled to draw and hit a silhouette target at ten yards in under three seconds. Even at this slow pace his shooting was still erratic. On the same exercise I was consistenly getting good hits in just under one second.
Even if the Law Enforcement Academy imbued some magical tactical knowledge into this officer (it didn't and couldn't, but let us pretend anyway) I would still have an additional two seconds in a split-second shoot/don't-shoot scenario to assess the situation and make a decision and still land a better hit, if that's what the situation called for.
Get your basic, fundamental skills and fitness down and your problem solving automatically becomes high speed.