I was shown an example of scaling a smart object. He took a hi-res photo into a 72 dpi psd, made the photo a smart object, scaled the smart object 60%, then converted it to a smart object again. The new smart object was then at 100%, which he scaled again 60%. He was able to incrementally step back through the scales, like undoing, though he'd shown various other things between.
1. is this necessary?
2. how do you step back through the smart object states?