The buying decision happens half a year early. Christmas ranges are committed in summer, so last year's figures per line are the only evidence available, and a shop without them is ordering on memory.
January reveals the mistakes. Whatever did not move in December occupies shelves and cash for another year, so knowing what sold when, at what discount, is what makes the next summer's order better.
A reservation is somebody's Christmas. An item held under a name for a relative who will collect on Saturday must actually be there, and a shop that loses track of holds creates the worst possible complaint in December.
Not all boxes earn the same. Big-brand toys are price-matched to almost nothing while wooden, craft and independent ranges carry real margin, and a shop measuring only turnover cannot see which shelf pays the rent.