It would be a huge timesaver, and save me some blunders, to be able to create new patterns based on existing patterns. Just tick a "from pattern" checkbox and it automatically reuses all parameters from an existing pattern. While you can hunt down and reference quantities and distances to the original pattern it takes quite a bit of time, and it won't take into account instances you've excluded. It would also ensure that you don't pick the wrong direction reference and have everything go haywire on subsequent edits.
My immediate thought is to add screws to a pattern of holes, but I'm sure there are plenty other uses for it.
