It is easy to download all the scenes of a pornstar if they only ever shot one scene...
You'd have to be a proper fan/superfan/obsessive of the person in question to collect each and every scene of theirs. Will there be people have done it? Probably. Will there be many who have? No.
But even someone who has the objective of obtaining every piece of material a babe has ever done will find it difficult to determine whether they have actually achieved or not because whilst there are many good resources online for listing out all the stuff performers have done, there is no one-stop shop that 100% guarantees it lists out every single thing. So even someone who thinks they have got someone's entire repertoire, might not actually quite have all of it.
I have 20,000 pics of her (though half are something like 95% similar because of Brazzers' shit) and there is probably a lot more of those out there.
Are you referring to their massive galleries (often like 900+ photos) a lot of which are like minimal difference between photos?
If you open them in an image viewer app and hold down the right button you can cycle through them like one of those cartoon flip books. Because so many snaps are taken with seconds / milliseconds in between... it's like watching a video rather than just looking at the pictures because you see them gradually move from one pose to another rather than suddenly move from one location to the next.