John Levine wrote:
Are fast, non-stop services allowed? For example, from Wembley Park to
Finchley Road on the Met, or Acton Town to Hammersmith on the Picc? Or do
stations only count if the train stopped at them?

Read all about it:

http://www.thetubechallenge.com/tube-challenge-rules

Is there a generally accepted optimal route for attempting the challenge
within these rules? Presumably there are certain parts of the network that
impose constraints so have to be done at particular times.

Robin