But, with walkthrough in hand, I'd take a look in the endings, and look some videos on youtube also. Going directly to the point: these docs and videos where made 2009 (most of them) and people enumerate these endings very fast. Then I came into the end for the second time, and reading subtitles I got a good one. But as the first time, the end was not as discribed - not the same sequence of dialog and movie. I'd wrote about in coments of a movie that shows all final talking and last videoclips, but they don't believe me, they think my game was hacked, but I got the PS2 original DVD.
I think if you follow a walkthrough, as a lot of people do, the end will be predictable. But this game is not so "arithmetic" as SH1, if you play by your own, different things may happen.
I believe a few people end the game sometimes and the rest was behind ignoring all possibilities of the game. My second end was very true with all my actions, If is a bug, is a smart one!