Great Eastern wrote:

What ****es me off most is when you want to go from Stratford to
Liverpool Street and you have to choose between platforms 5 and 10 (so
far apart).

IIRC most trains to LST from Stratford which are on the Up Main (P9) are
Set Down Only. P5 is the Up Electric which are the ones you should board.

Not totally - a lot of services seem to switch between the fast and stopping
tracks with scant regard for this. It's not even consistent where on the
line they switch.