I agree with tegeus-Cromis, but when I was younger I thought the similar names added to the epic feel. I guess I did not really care that if Conan was in the title, then he wasn't really going to die.
CS Lewis and JRR Tolkien did not bother with similar titles and I love their works. On the other hand I also love RE Howard's Conan books by Lancer/Ace in the 1970s where every book began Conan... and I loved ER Burroughs' Martian stories, by DelRey with the Michael Whelan art, where every book (except Llana of Gathol) ended of Mars.
I don't know that I've ever started a series based upon the fact that the books had similar or thematic titles.... except for David Eddings' Belgariad. I've come to learn that books I liked had similarly titled sequels, GRR Martin's A Song of Ice and Fire series. And I've actually gone into reading a series cringing at the titles of the subsequent books.... Harry Potter and The Broken Empire come to mind. I loved the former and disliked the latter.
I think the marketing can be positive or negative on this title thing. All of Shakespeare's histories are shortened to just a name and number. I'd like to bash Rick Riordan's Percy Jackson series because the title screams "If you liked Harry Potter, then read this!".... but I think using a child's name around which to develop a series goes back at least to Nancy Drew and the Hardy boys.
I mentioned Michael Whelan's covers for ERB above. I was always ten times as likely to read a book based upon it's cover art than it's title. John Carter, Conan, Riftwar, Dragonlance, Prydain Chronicles, Shanarra, The Iron Tower trilogy, A Song of Ice and Fire, Kingkiller Chronicles as well as others that I did not continue... Lord of the Isles, Taliesin, Witch World, Orcs, Across the Face of the World, The Dragonbone Chair, and more.