Its not in FGW▸ finical best interest to stop an pick up with unscheduled stops as the train is then delayed by the TOC▸ and they have to pay NR» for that as it was an NR problem NR will pay compensation to FGW but you and I as passengers won't see a bean of it
I had a look at the Live Network Updates on the FGW website yesterday at about 09:00 and there was at least one entry saying "This train has been revised, it will no longer call at Twyford, Maidenhead, etc." So never mind adding extra stops to trains, it looks like FGW were actually removing scheduled ones!
Just two of the many tricks the TOCs get up to ensure they keep up their performance figures.
One other which I believe
SWT▸ was very fond of was terminating trains short of their final destination to get them back ontime for their next journey. Provided it's completed a certain percentage of its journey the train is niether cancelled nor late.
Another, often referred to in the "Coffee Shop" is excessive timetable padding so that a train can be 30 late during large parts of its journey but arrive on time at its final destination.
The really sad thing is that there is army of accountants who do nothing but argue who is to blame for any late running or cancellations and, therefore, who is finacially penalised. However, they don't help improve the perfomance one little bit.