I think it would be really useful if we had an option, somehow, to chisel once.
As in the chisel would recognise whether the block has already been chiselled or not, then chisel if it hasn’t or don’t if it has.
I think anyone creating larger farms would likely understand where I’m coming from with this.
Useful in other areas too
Not sure how it could be incorporated, either another boon (sigh) or a new tool (type of chisel).
All they rly have to do is incorporate an auto trigger feature disabled on chisels. That way if you click and hold while chiseling the chisel would ‘fire’ only once. I think that would solve your problem 
If youre planning to hold down your button while going over multiple blocks that would be tricky, because the chisel would have to ‘remember’ what part was chiselled out and do it for every next block. Would be cool though!
What about a copy-cat chisel forge boon? Hit an already chiseled block to pick the shape and then use it on unchiseled blocks recreated the shape in one hit =) pick a new shape by hitting a different shaped block.
That way you don’t have to worry so much about hitting the right corner / edge to get the desired shape.
That would be a really nice feature (chisel) 