100's of times camping & bushwalking.
We had top-quality 'Paddy Pallin' double & single one's, suitable for fairly cold conditions.
One time, April'76, was camping beside Myall Creek, Roma, Q'l'd., enroute back from Carnarvon Gorge.
It was very cold, so much so, that a thick layer of ice was on 4WD, & fly sheet of tent, next morning. Apparently it was -5 degree's!
We'd bedded down in 2person tent, with, from ground up.......
Thick, clear plastic sheet, space blanket, thick layer of newspapers, air bed, double sleeping bag, spread out, then we inside single sleeping bags, wearing, thick woollen socks, thermal underwear, track suits, leather, wool lined gloves, balaclava's, then double sleeping bag spread over top of us, AND we were STILL cold!
Bearing in mind top of single sleeping bags could be pulled around head for warmth!
It was bee freezing. We've never been so damn cold!
Hubby got even colder, month later, on ARes Course at Charleville, Q'l'd., as he 'phoned me to post MORE thermal underclothes to him!
Was always very comfortable in, or on top of, our bags, dependent on weather.