Re: few days?
"Applying Moore's Law, that's about 25 cycles of exponential performance improvements. I.e. today it took 4 days, but 18 months ago it would have taken 8."
That's pretty good. The fastest hashing AMD GPU 18 months ago was an R9 390x with half the hash rate of the VEGA which came out about then. VEGA also uses about half the power to work twice as fast.
There are farms of these VEGA cards mining crypto. Even a 4 card rig could probably do it in a day.