AFAIK that's how the "individually downloaded" apps behave, but Toolbox apps -- for good or bad -- appear to be whole-hog downloads each time. I strongly suspect that's due to the roll-forward and roll-back behavior in Toolbox. Although unless my mental model is wrong, it should still be possible for Toolbox to have release-1 in a directory and _create_ a release-2 directory based on (release-1 + update patch), just into a new directory instead of in-place