When do you stop?

I was re-reading some of the material in the excellent anthology Priestesses Pythonesses Sibyls this week, and pondering a question.  When do you stop your research?  I have a tendency to want to go back as far as you can possibly go with any trail of knowledge, which has caused me problems in the past, and is not always good for meeting deadlines!  However if you go all the way there is less chance for something to be misrepresented.  To illustrate consider the Delphic Oracle, discussed in several of the most enhjoyable essays (for me) in the anthology, namely those of Caroline Tully, Bolina Oceanus and Sorita.  The Delphic Oracle was sacred to Apollo, who took over the Oracle from the serpent Pytho, called a goddess by some.  Apollo and his twin sister Artemis killed Pytho due to its merciless hounding of their mother Leto (on the orders of a jealous Hera) when she was pregnant with them.  This has been sometimes cited as an example of how the patriarchy took over an old goddess site – an example of selective interpretation as not only did Pytho hound the goddess Leto, but Artemis also took part in the killing, it was not just Apollo!  Further, if we follow the trail back further, as I like to do, we see that before Pytho, the Delphic Oracle was originally sacred to Leto’s mother (and hence Apollo’s grandmother), the titan goddess Phoebe.  From this perspective we can see that Apollow as actually reclaiming a family heirloom, as it were!  Although of course some sources suggest that other goddesses held the shrine before Phoebe, so it get even more complicated again!  At this point you either start tearing at your hair, or follow the trail any further if you can!