d wrote:

And how many people do you put out by doing that? Remember - just because
something is beneficial to you, it doesn't mean it's beneficial to others.
What if you saving 3 seconds makes 40 other people delayed by 1 second each?
You would have selfishly exchanged 40 people/seconds of other peoples' time
for 3 people/seconds of your own.

Unless they are changing onto the Central line and miss their train as
a result of my action then I'm not really delaying them, whereas if
there is a train there then it's more urgent that I need to get through
to it. It doesn't help the fact that at Tottenham Court Road you then
have to walk quite a way up the platform you don't wish to use to
switch over to the Northbound one.

If there are people it's probably because there's a train there and I'm
not saving 3 seconds, I could be saving 8 minutes or more knowing the
Northern Line.

The signs are usually there for a reason.

To convenience those from the South. Probably the person who designed
it travelled in from the South.