A long long time ago i worked in a repair shop while in college. Fixed a lot of car radios that used TO-220 transistors. I ordered the lowest voltage of the series type. With a voltage breakdown tester I sorted them by voltage. Actually there were only two types, a few low voltage ones and well over 90% were more than the maximum rated voltage for the series. The tested higher voltage ones were used for higher powered amplifiers. Every once in a while there was one with a squirrelly curve that went right into the bin. Point is manufacturers don't make a good, better, best type of a die. These qualities are sorted out when needed. To fill orders of the common stuff everything is shipped out. In less than a second they can sort out parameters that statistically indicate performance under certain operating conditions. As said before, actual cases do matter. If your circuit out performs typical published specs it will likely work well at extended temperatures. Chances are with you even if you don't test. They don't try to make bad parts.