Woke up the first morning of my first ever elk hunt, and it was 9 degrees in the tent. It took some courage to get out of the bag that morning. Needless to say, the heater ran all night, every night, for the remainder of that hunt. We use the small catalytic heaters, and try to set them where the heat is directed under the cot, and rises up evenly under it. Bottles usually don't last all night, so I make sure there is a spare within reach so i don't have to get out of the sleeping bag to change it out.

I will also throw a couple of hand warmers under a pillow to keep it from getting too cold. One or two at the bottom of a sleeping bag can keep your feet nice and toasty.

50 degrees, to me, is perfect tenting weather. Only need a heater to break the chill in the mornings, but great to sleep in.

I have a 0 degree canvas/flannel lined bag, and 4 of the old heavy wool moving blankets. Temperature range dictates how I arrange them, but I can stay warm in very cold weather when necessary. What you sleep on is as important as what you sleep in or under.

Another fond memory!

I agree that it's all about the bag. I have a 0 degree mummy bag and have been nice and toasty at night even when the temp drops into the low teens. Going to take a leak in the middle of the night, that's a differerent story!