I think after doing 100+ passages of any given subject, you will are very likely going to encounter some of these topics in one way or another. Some topics are so good to test a broad range of knowledge that mcat test takers may find compelled to use (the Haber process is one that comes to my mind). Besides, I've read posts by recent mcat takers mentioning that their test had a very similar passage to one of the TBR practice passages.
So, yes, the more passages you do the better you get at reading passage faster, anticipating the type of questions will be asked, and the more you become familiar with different topics that may show up on the test.