In message , at 20:57:41 on Mon, 1 Apr 2019,
bob remarked:
Ian Clifton wrote:
Let’s suppose you’re going from Reading to Hanwell. You might have to
make as many as 2 changes (at Slough, and Hayes & Harlington), to reach
a station you’d simply pass through if you didn’t change. What’s the
most such changes a (sensible & perfectly informed) passenger ever has
to make?

How about something like Thirsk - York - Peterborough - Stevenage - Welwyn
North?

Apart from there being a regular service from York to Stevenage, meaning
two changes eminently possible.

Journey planners also offer the occasional one-change, at Kings Cross.
Which goes back to my earlier question about how challenges like this
interact with doubling-back.

Sun-Fri Shippea Hill to Ely[1], for example, always requires doubling
back; but still results in only two changes.

[1] And of course anywhere further east on that line, *to* Shippea Hill.
--
Roland Perry