There are fifty-two, sometimes fifty-three Sundays in a given calendar year. When I multiply the twenty-five years I have been alive by the approximately fifty-two sermons I listen to yearly, and adding any other conferences, camp meetings, sermons I view online, the result is more than 1300.
Since the age of ten I have collected sermon notes of every sermon I have listened to partially because I am a nerd and I know it helps me retain the material, but more importantly I knew from a young age that I would be preaching some day and I wanted to remember how others preached. Sure, I have hundreds and hundreds of church bulletins and programs with notes I could reference to recall my memory, but when I think about it, I can only remember three or four sermons.
It is not that I can recall the sermons in their entirety; I remember how they were presented, and how they impacted the preacher.