Thanks. It is, I think, a uniquely American concern, since it's long been
common for writers in the UK to write a goodly portion of any season;
McGoohan did much of The Prisoner (under a variety of names), and Terry
Nation wrote the entire (and some say best) season of Blake's 7, though that
was only 13 episodes. (I believe the adaptation of I, Claudius, at 12 hours
or so, was done by one writer...and it's the best thing ever made for TV, I
think.)

jms