So i do kinda enjoy this on but thats just exploiting.

so when using the iron spade shovel. you can continue to use it after it breaks, only if you dont stop shoveling. (depress mouse button)

you can use it indefinitely as long as you have the dig button pressed before it breaks. but once you stop digging after its broken. it now become broken. 

I do alot of digging and noticed this pretty fast.