it does not "reset" until the vein has been emptied and respawned
but if you have it so the ore coming out is random each strike, then it is useless, because that has overwriten the vein properties, and just selects random ore (this was an issue with Daats system)
same with the gargoyle pick axe then also
this is because it "picks" the ore to give AFTER it has decided what is comming out
either turn random ores off, or keep the tools as useless
(by random ores i mean that each hit with the pick axe you can get a different random ore, not that the veins are randomized with each restart)