I have a certain fondness for authors like Sue Grafton for that very reason.
Besides, it will make life much easier for future researchers. I've been working on a major project -- compiling a list of every boys' series book (think Tom Swift, etc.) prior to 1940. Mostly, this involves spending a lot of time on Google Books and the Internet Archive, rummaging around in the backs of bad scans, looking for the lists of other series by the same publisher so I can figure out where "The Boy Geniuses Save the World" fits in its series. So, series authors, think of the future! Don't make your future fans suffer like I have! (if I could call up Edward Stratemeyer's ghost, I'd scream "you should have numbered the damn things!!!" at him).