I don't think that adding 10 minutes to a London - Sheffield journey will put people off from the train. Although journey time is one of the reason why people take trains, adding 10 minutes to a 2-hour or more journey is just a minor change, but if we can take away two changes for people boarding at St Albans / Luton Airport Parkway / Luton, many can be attracted onto the train.
I don't think that adding 10 minutes to a London - Sheffield journey will put people off from the train. Although journey time is one of the reason why people take trains, adding 10 minutes to a 2-hour or more journey is just a minor change, but if we can take away two changes for people boarding at St Albans / Luton Airport Parkway / Luton, many can be attracted onto the train.
A 10 minute journey time increase
is a big deal on London Sheffield (and, for that matter, London Derby and London Leicester). Thats why the industry spent hundreds of millions of punds reducing them a few years back.
The market between London and Leicester / Derby / Sheffield is an order of magnitude larger than the market between St Albans + Lutons + Bedford and these three places. And many people in the latter market already make the journey by rail, in the St Albans case often via London. The gain in passengers and revenue from providing the latter with journeys with one fewer connection would be offset at least 10 times by the loss in passengers and revenue from the longer distance routes. And the longer distance oassengers would all have longer journey times to their disbenefit. And it would cost more to do (longer journey times costs more).
In short - fewer passengers, lower income, longer journey times, higher costs. Overall bad for passengers and bad for the taxpayer.