Oh good grief, they actually trigger
other springs at the same time if you happen to be in normal gravity when triggering them, it turns out:
In particular they fling down only the next spring in order of item placement in the map. ...but they do this only when you're in normal gravity; when you're in reverse gravity they don't do this at all.
Curious findings, can't for the life of me figure out why this is happening firsthand.