Well done, but why 1-4, and not 1-2?
Because for some odd reason it was cheaper to do it 1-4 than 1-2.
I seem to remember that it worked out cheapest to maximise the travelcard
part.

I used to work out which combination was cheapest and it doesn't work out
for all stations and/or rail companies, and often the changeover point was
different each year.

This year cheapest is to Z4 and saves £332 from Potters Bar. If you're in
Welham Green it saves £472. All combinations are cheaper than the off the
shelf ticket (although there is the caveat that the train must stop where
the ticket changes over - less of a problem from Welham Green where the
train is all stops anyhow).

I'd love to be able to just walk into the booking office and buy the most
suitable ticket for my needs without having to go through this nonsense.

Why can't they just sell a ticket valid "POTTERS BAR & R1234"?

D