I believe this subject has been pretty well covered, however, I'll add my tuppence.
I usually load in the basement before going hunting. My hunting grounds are right behind the house, so there usually is no reason for me to carry a loaded gun in the truck. During deer season, a felt wad is loaded, over powder, to prevent fouling the powder with mutton tallow patch lube. A strip of electricians tape covers the muzzle.
We usually don't have wide variations in temps, however, I usually leave the gun loaded, until fired, on an enclosed back porch. Frizzen stall covers the frizzen, and a toothpick blocks the vent.
Personally, I don't have a problem leaving a loaded gun in the house or car. My oldest was taught proper gun safety from an early age. He received a perfect score on the hunters safety test, most of which was old information, for him.
My youngest was severely developmentally delayed and didn't have the ability to discern real from toy guns. The 1911 was kept with a loaded mag, but with an empty chamber. James didn't have the strength or manual dexterity to jack the slide, when tested with an empty gun. The 45 was also kept where he could not reach it. I even had to stretch a bit to retrieve it, so it would have been impossible for him to get to.
Fortunately, I have never had to use a gun to defend my home. I was once confronted by a coupla punks in my woods, but never threatened in my home.
The coupla times we have had to call the Sheriff, response time wasn't all that great. One response took 20 minutes, and the fastest time was over 5 minutes when a truck load of kids hit the telephone pole near the house. I reported possible injuries, by one of the kids being ejected from the truck, and still not what one would call a real fast response. So much for fast help in the event of an emergency.
IMHO, its better to prepare the whole family to take care of one's self, in the event of an emergency. IMHO, part of that preparation is teaching the whole family proper gun safety, from an early age.
In the very few instances where self defense became necessary, there was no time to retrieve or load anything. If not for a gun immediately at hand, I would have been in a coupla real serious situations. As it was, the mere presence of a 45 cal hole lookin' at the punks who were up to no good dissuaded them from "mischief," with no shots fired.
IMHO, keeping a loaded gun anywhere all boils down to common sense and reasonable safety precautions.