So I was at BayCon this last weekend and one of the panels I went to was on pseudonyms. One of the things the panelists talked about was the way so many writers are actually forced to change the name under which they publish, because the buyers' computers have slashed their purchase numbers to the point where their old name is no longer commercially viable. Two of the three panelists had been forced to do this, for exactly this reason (and were selling well under their new names, so obviously the tanked buying numbers weren't just because they were sucky writers).
This was interesting to hear because I remember reading Holly Lisle's series on this topic, from about a year and a half ago. (Link goes to the first, others are linked at the bottom.) Considering how much crap Holly took from various people who somehow got the impression that she was trashing the individual people who actually work at bookstores (and seriously, I have no clue where they got that because that's not what she says, anywhere), it was pretty cool to see three other writers sitting on a panel nodding and agreeing that this is absolutely how the industry works.
Anyway, with the caveat that this all applies to print publishing (and makes me happy to be an e-published writer for right now) some interesting points.
One: A writer has about a 75% chance of having to change their pseud at some point, and quite possibly more than once. Even assuming the estimate is most valid within the SF/Fantasy field, that's still a fairly honking big number.
Two: If your publisher still believes in you once the buying computers have written you off, you might be invited to keep writing for them under another name. If not, you're out, but you'll still need to use another pseud when you go trolling for a new publisher.
Three: The first six weeks a book is on sale is the critical period. These are the sales the computers look at when they decide how many of your next book to buy. So readers who wait until a series is finished before buying it to read all at once, especially if they delay because they've had too many series they were enjoying cancelled in the middle, are actually helping create the problem they're trying to avoid. :/
Now, I'm going to assume that if you're King or Gaiman or Clancy and sales are disappointing on your twenty-sixth book, that whoever is in charge of the purchasing software for B&N or WalMart or whatever will probably be willing to go in and do a hand correction so that they don't only buy 5000 copies of your twenty-seventh book, 'cause, you know, you're King or Gaiman or Clancy, and even your sucky books sell pretty darned well. But for the rest of us, one less-than-great sales total six weeks in can be devastating.
This is also another area where a small press can be advantageous to the writer. You might not have much chance of ever hitting the NYT Bestseller list if your book came out from Tiny Obscure Press, but on the other hand, TOP isn't expecting you to sell 50,000 copies, and won't dump your butt if you only sell 3000. Heck, TOP would probably be delighted if your book sold 3000 copies, and if you're a good writer and are willing to feed some fuel into the marketing machine, you can probably sell that many just through independent bookstores, especially in a field like F/SF where there are a lot of independent bookstores which are dedicated to your genre.
If you're with Baen or Tor or whatever, though, sales figures in the 3000 range means you'll probably be kicked to the curb. And that's likely to be true even if the rotten showing was the fault of the publisher; if they did some major ball-dropping on the marketing, for example, the numbers are still your numbers. Even if your previous book sold two or three times as many copies.
Oh, a funny: one of the writers had changed her name for the usual reason, and pre-order figures on her next book were very good. Until one of the big chains (either Borders or B&N, I forget which) got the word that Mary Newname was actually Susan Oldname. Someone who probably hadn't gotten laid the previous night added that bit of info to the sales program and the chain slashed its order down to pretty much nothing. [headdesk] The writer in question suggests keeping the secret until about six weeks before the release date; at that point you can blitz the independent bookstores with the news that yes, Mary Newname really is Susan Oldname, that writer whose books they liked before, so please order more of her books and let readers know about the connection. Six weeks prior is too late for the big chains to change their orders, though, so you're safe from that. And once your new book starts selling, those are the figures they'll use to calculate their next order, so it doesn't matter at that point if they make the connection.
And another funny: one of the other writers kept writing in his old series after he'd changed his name. [wry smile] Bob Newname's books were about the granddaughter of one of the characters in Tom Oldname's series, set in the same universe and all. This was all right with his publisher because all that mattered was the name on the book cover. But Tom got some e-mails from concerned fans asking whether he knew that this Bob guy was plagiarizing his universe. Umm, yeah, he knew that, but thanks anyway. [facepalm]
Which just goes to show how ridiculous the system is. But so long as the big chains, where the vast majority of paper books are sold, prefer to have their buying process completely automated, this is where we are. All we can do is game the system as well as we can.