I'm one of those ancient types that still records Doctor Who episodes on tape and edits out the commercials while doing so. Anyway, while I agree that both
Doctor Who and
Torchwood generally stand apart from one another, I did record the
Torchwood: Children of Earth series between two episodes of David Tennant's run, and while his Doctor was noticeably absent during
CoE (and a point was made of that), it was a fine case of
Doctor Who and
Torchwood fitting seamlessly together and gives backstory to what Captain Jack was doing moping about that alien bar in Tennant's final episode, IMO.