[jefftk]

The ones that are 25 pieces x 40 pieces are really 1000 pieces. But some puzzles are 27x38 or other more square form factors.

[Retric]

25x40 is rarely used because non square piece give a lot more info about placement and a 25 X 40 rectangle is almost twice as wide as it is tall. It’s rarely the right kind of aspect ratio.