Comparing the product life cycles of different categories also offers valuable insights. Even after experiencing consecutive years of declining annual shipments, the smartphone industry does not consider itself fully saturated, as the demand for device replacement and upgrades is perpetual. By the same token, the installed base of
full size sex dolls is significantly smaller than that of smartphones, and the average product lifespan is merely two to three years (due to factors such as material degradation and hygiene concerns).