Found myself using only the pickaxe in the last run. While the mining efficiency is perceivable, I felt like there was no real need for the continuous switching. It's also pretty easy to soft-lock youself in this game as mining upwards does not feel prettly reliable, you may consider not only tool but also jetpack upgrades - similar to how "A Game About Digging a Hole" did it. The soundtrack and the intro text was funny though. Well done!