After reviewing hundreds or photos, I have seen quite a bit of evidence that German tankers used extra tank tracks as improvised armor. As a scale modeler, I was shocked to not find similar photos for the T-34.
While the T-34/85 has been documented with bedspring armor, I struggle to find good data regarding tread usage on the T-34/76.
Anyone have sources or photos?
There is a misconception around "bedspring armour". It was not improvised armour made out of scavenged mattresses or bedsprings. It was purpose made spaced armour to protect against Faustpatrone and similar weapons, closer to the German Schurzen than the track link armour you see in photos.
The Red Army did use spare track links as armour, but this use came from the top rather than through grassroots initiative. In 1944 trials were held to determine that the addition of spare track links to the upper front plate of a T-34 tank reduced the penetration distance against a 75 mm Pak 40 gun by 200 meters, so five spare track links were carried on the front of T-34 tanks and derivative vehicles after that. You also see track links tucked behind handrails in photographs, but it's arguable that these are simply spare links rather than improvised armour, as only a couple were carried on the side or behind the turret.
Sources:
http://www.tankarchives.ca/2014/06/panzerfaust-protection.html
https://warspot.ru/17215-teoriya-bronetankovyh-zabluzhdeniy-pobednyy-45-y