More voltage you need to pump through the CPU the more of a chance you reduce the lifetime of the CPU. More volts is obviously more heat, too. Really isnt advised to put so many volts through especially 1.4V. This is why TTL did a guide on how to fully optimise your overclock and achieve the best, with the least amount of volts.
I guess the only time you would use such a high value is benchmarking, but for everyday use, the fewer the better.
1.22volts for 4.8 is damn good in my eyes.
Virtually unheard of.... There are others, but they are so few, and in most cases their testing methodology is usually light-duty, and not actually stressed.
Dude completely blew the bell curve.
Some people say you can run 24/7 up to around 1.35V, but I try to keep it below 1.300. I feel safe running 4.7 @ 1.295, but that's my personal limit for 24/7 on a freaking USD$330 chip, we aren't rich.
IMHO, on the other end of the scale, TTL's 4.6 GHz max 4790K is kinda low-speed at a high voltage... 4.6 is on the low side of the mean on the curve. Either it's rare to see them top out so low, or people who have them aren't really saying much... The average high-end is 4.7-4.8 stable. If you look at the charts, and spreadsheets, I'm probably on the good side of the mean on voltage, but still in the main pack on speed.
It's all pretty much luck of the draw, these chips are like cats. They may look similar, but are quite different in personality, thus the term "Silicon Lottery", which was co-opted by that company selling cherry-picked ones at a premium price (great for instant gratification and e-peen envy, but, IMHO, takes most of the fun out of the OC. 80% of the fun is finding the limits on your own).
To summarize for the uninitiated, they are SODs. "Smoke Operated Devices". It's all cool until you let the smoke out! :cussing

and 1.4V+ is universally considered the starting point for that, at least when you are not on extreme loops or something below ambient. Otherwise it's risky, usually good for quick benchmarking, but nobody in their right mind keeps it that high in voltage).