WHen you click on a rock to mine, would it be possbile to add "Mine till exhausted" in addition to Mine? That choice would allow you to mine the rock until it's gone or you don't have energy to complete the next mine action.
I can see this being rather useful to a lot of players, and, since we already have upgrade cards that let us fully disassemble and assemble machines, having this functionality as an upgrade card wouldn't be out of line with what's already in the game.