Just reading from some of the stuff here. Baking isn't the solution for ill fits. The boot shells themselves aren't that formable unless you take a heatgun to it.
Baking is to speed up the lining material packing process. There is about roughly 5mm width in the boot that will give. But the foot last shape won't change.
If you look at Scott Van Horne's TF9 tutorial on reducing boot by 1/4 size, he's an artisan and a hacksmith, I wouldn't be surprised if boot size issue are from those method, work for some, and not others.
If you have 70 percentile feet. Med high arch, long toes, big heel bone, you won't have issues. Heck any brand works.
But any feet outside of those parameter, man, no one knows the pain, literally.