Yes, for the right grade and volume, very big pits are possible, eg Superpit in Kalgoorlie. it just needs to be economically viable, and sometimes it takes a while to remove the overburden for a cutback or to get down to where it is, all the time you are exposed to a varying commodity price. In GXY case lithium looks good for a while.
I used to crunch these development numbers on mining resources for a living, in a previous career.
