It would be nice to have different versions of precision grind mode that you can cycle through for different situations:

Functional: only grinds out materials that are not necessary for the block to be functional.
Non-Functional: only grinds out enough to make the block non-functional.
Hack: only grinds out enough to hack the block.
Placeholder: grinds out everything except the last component.
Targeted Block: completely grind the currently targeted block and stop grinding when it's gone. (This is currently the only function of precision grind mode.)
Targeted Grid: only allow grinding of blocks in the targeted grid. This will make it easier to grind down small grids that are sitting on large grids. Once one has ground down the bulk of the grid they can switch to targeted block mode to clean up the bits that fell off and became separate grids.

Build states: maybe also allow targeting of a specific build state for those who like to use the different build states for decoration. Alternatively, this could be a precision mode for the welder.