Don't mean to beat a dead horse, but I have to add something to this whole debate. The majority of my clients have no white spots or anything on their nails when I remove their shellac. One client whose nails look terribly damaged, I can only attribute to age perhaps? When I remove her shellac I solar oil first because her hands look so dry, I only wrap for 6-8 minutes and when I remove the wrap, the shellac literally jumps off the nail in one piece. No stick, no scrubbing. Yet her nails are full of white spots.
My mother, on the other hand, takes twice as long to remove that any other client. It's always a struggle to get her shellac off. No one else, just her. And when I do finally get it off, her nails look absolutely perfect. Not a spot to be found, ever.
My point is that every person is different and I don't think the answer is one size fits all.