> My kids have a photographic memory of each of those special pieces and which set they came from. They’ll remember them and search until they find that exact piece

I had the same skill (still do). Imagine following the instructions the first time. A part you're encountering for the first time stimulates the memory. I knew my collection like a dragon's hoard. For instance, I owned twelve white 1x2 tiles, all from Coast Guard Station, so that was the limiting piece when building tiny space-fighters...