I personally don't see how keeping a dog in a crate, during a keep, is the "worst mistake." There are a lot worse mistakes to have happen than that. Dogs in a crate aren't allowed to run around and waste energy. They are confined to a small space of which they can stand, sit, or lay down and rest, which is the most important thing in a keep. You can let your dog run around in the house some if you like. I'm certainly not advocating the crate as a sort of jail cell, but if a person keeps a dog in a crate during their keep, it's not the worst mistake by a long shot. A keep isn't about what a dog wants. It's about having the dog worked and rested for possibly the fight for it's literal life, so at that point what a dog wants is pretty much irrelevant. What the dog NEEDS should be the main focus of any keep.

All of that being said, I don't keep all dogs inside as they're all different. My Buddy dog would immediately piss in his crate as soon as he stepped one foot inside the damn thing, and it didn't matter if he'd just took a big leak outside or not. He was just a nasty dog in the house, so he stayed outside in a heated doghouse. Some dogs I keep outside at an isolated spot during the daylight hours, and then I bring them inside at night. There are varying reasons for why a particular dog stays certain places while others do not.

On the flip side of the cold weather debate, I don't like my dogs staying outside in hot, humid weather either. Sure, it's warm outside, but they also have to contend with mosquitoes, fleas, ticks, and lord knows what other bugs throughout the time outside. It's hot out, so they're constantly having to work to keep themselves cool.

For my money, a dog inside during a keep is the best thing to do at any time of year unless you have a dog that simply will not cooperate.