Abort while reading data should end immediately
dtt wants to wait until the next data chunk is read before aborting a test, but this could be a very long time if NDS is busy or it's reading from tape. These long pauses are perhaps the most likely time to abort.
Worse, diaggui looks like its aborted, but will refuse to start a new test until the previous test is actually aborted. There is no indication when this will happen, or when it has happened.