While pulling weeds in the garden the other day I made an interesting observation. It doesn't take the same amount of time to pull each weed. Some come out of the ground quickly while others seem to be held in with Mighty Putty. I am sure the same would be true of getting copper and silver deposits out of the ground. Or even for skinning a freshly killed animal.
I feel that in order to make most tradeskills more realistic the "timers" should be a random amount rather than a set number of seconds.
Now, I don't know what is more sad; the fact that I think of things like Warcraft while weeding the garden, or that I was comparing Crabgrass to Felweed.