There were a few times earlier in my leveling of miner where I saw people mining superfast as well. And I was like hmm that must be some kind of a gatherer skill they have cross-classed to speed things up or something. I never did really research it to find out. But I havent seen that sort of thing in a while now, but I have seen what your talking about. I'll be mining at my normal regular pace and someone comes along and hits it double my speed easily, and gets done.