Originally posted by Letozeth:

Pickaxes now hit everything within striking range, much like the axe does for trees.
This however also splits damage a bit. But overall yes, you will will mine a lot faster.

Thanks for the explanation, I knew something was different, but not quite what.

It certainly works well with muddy scrap since it doesn't take much damage to break in the first place, just all the tiny little bits you had to individually hit before.