In message , at 22:28:09 on
Wed, 16 Jul 2014, Richard remarked:
All they say is that using Oyster is cheaper than either:

*a* paper ticket (probably some form of Travelcard) that would have
enabled all your journeys that day.

a series of paper singles.

A lie of course. if I want cheap travel around London I invariably do better
with a paper travelcard.

A lie?

See
https://www.tfl.gov.uk/fares-and-pay.../price-capping

"Capping compared to Travelcards

If you make several rail journeys or a mixture of rail, bus and tram
journeys in one day, daily capping is usually better value than buying
a Day Travelcard.

Note it says "a" Travelcard.

It might be cheaper for example to buy a 1-4 Peak travelcard plus one
4-5 off-peak single, than the cost of a 1-6 peak cap (if your journey
fitted that travel pattern).

Compare these daily caps and Day Travelcards (at adult rate):
Journeys in:
Peak Off-peak
Cap Travelcard
Cap Travelcard
Zones 1-2
£8.40 £9.00 £7.00 £8.90*
Zones 1-4
£10.60 £11.40 £7.70 £8.90*
Zones 1-6
£15.80 £17.00 £8.50 £8.90
Zones 1-9
£19.60 £21.00 £11.60 £12.50

* You can only buy an Off-Peak Day Travelcard for Zones 1-6 or 1-9. If
you're only travelling in Zones 1-4, capping will be better value"

So it seems to me that it is always cheaper on Oyster. No lie. I
wonder why they only claim "usually"?

How about an outboundary travelcard (whose uplift varies, admittedly),
especially if bought with a railcard?
--
Roland Perry