Quite apart from any matters of railway operational practicality, any extension to the dwell time at OOC translates into a journey time extension. To most of us that one minute extra would be meaningless, but to those people driving a computer model which predicts income, there is a correlation between journey time and patronage. In theory a longer journey time makes the journey less attractive, so fewer people will use it. So sitting for an extra minute on every train at OOC damages the business case quite significantly.
In practical terms, the one minute does make a difference where some passengers are making a connection - it may make the difference in making an advertised connection at, say, Manchester Piccadilly possible or not.
