Every time you print a page, the vibrations will send minor tremors to your lenses which will go out of alignment a bit and the screws get unscrew bit by bit, by the time you go thru a stack of A4, all your lenses would had fallen apart. Glued parts might dislodge and fall away too.
Such is the power of printers. Such, is the power of paranoidism and love of perfect condition gear. Such is...
Ok sorry.