The shaft that the ALDA actuates is spring loaded. When the ALDA is installed, it pushes the shaft down (leaner). As boost increases, the capsules inside the ALDA compress, allowing the shaft to move upward (richer). So at idle, no, it's not "doing" anything until boost builds. There's no connection between the pedal/linkage and what the ALDA does inside the pump, meaning when you floor it the ALDA shaft isn't moving - it's separate. Kinda hard to explain... the Bosch injection pump books are somewhat helpful here.
However if you remove the ALDA completely, then it would give full enrichment off-idle. There's another thread going at the moment recommending ALDA removal from all turbo cars, which I don't quite agree with, but a number of people sure do like the idea. Go figure.
