Regardless of slight variations we can still notice "trends" if people give such feedback.
For instance, the threads where above 2.3V DDR2 was mentioned as being unsafe for a normal desktop 24/7 with a year longevity in mind, actually did help us, even though many killed those Microns at 2.1V (me too) but most didn't and were safe till around 2.3V real when cooled although no more. I would then stick to advising that much maximum for it and not anymore even though I've rallied 3V normal air into them for over 3 hours once and above 2.3V regularly for benching, I would never advise it. The trend would be similar in DDR3 although different volts.