Do you think authors using pen names just throw a book out and if it doesn't do OK they abandon the pen name and try again until they have a hit under that particular pen name, and then the fans come and rabidly gobble up anything that pen name produces?
How many 'failed' pen names have we seen that the original author is open about?
But when an author does well with a pen name, she'll most likely claim it. Sometimes you even get on the cover 'such and such writing as blah blah'.
Do you think that might be how it works?