You can dig on stone patches endlessly with no stamina reduction. (means if there is a coal patch below = endless amount of coal with no stamina reduction or animation of digging..)
you just stand there like a lemon. and magically rocks appear in your inventory.
Do not know if this is working as intended but literally could stand there and dig up 100x piles of coal. (this allows people to get ore upto 95% in smelter then use one 100+ql coal to ensure its high ql metal. It ensures people have a unlimited supply of high ql coal by using a unlimited supply of low ql coal... if you catch my drift)
If you change this; being able to lower the rock level doesn't seem right, could you not make it like clay in shallows? you can only dig a couple on each tile until it regen's etc?