View attachment 153834
Description: A map from OpenRailwayMap showing the speeds between Rugby, Coventry and Nuneaton. The speeds shown are said below.
A lot slower, Rugby to Nuneaton is 100/110mph. Coventry - Rugby is a bit quicker at 125mph (Pendolino) but Coventry to Nuneaton is a slow 45mph throughout.
If we assume that Rugby to Nuneaton or Coventry it's the same time (even though you've said Coventry is likely to be a little faster) 10 miles (and the road distance is about 9 miles) would be about 14 minutes.
If there's a train at 12:00 from A which arrives at B at 13:00, with the following train being 12:10 arriving 13:25 and the train after being 12:30 and arriving 13:30, people will still use the middle train, as it leaves later but arrives earlier. Especially if the middle train then goes into place C which isn't served by either of the other trains and especially if the fastest journey time to place C is to change from the first train to the second train.
Possibly, but planning Leamington Spa - Coventry - Nuneaton to time well with a 2tph LNWR Trent Valley would also serve the market well
Potentially, but only if it connects well with services people wish to connect to. If they always arrive 5 minutes after the onwards connection, then you've just added 25 minutes to the journey time and few will use it.
Are you proposing a London - Liverpool via Coventry? I'm not really sure what the purpose of this service is. Coventry - Crewe is served by the 1tph Avanti via Birmingham. Coventry - Birmingham wouldn't be that quick going that way compared to a change at New St or Nuneaton.
Served by 1tph doesn't mean that it's well served, if there's no scope for a more frequent service via Birmingham adding a second train (even if it's 15 minutes slower) would make travel easier.
However Coventry to Crewe is 1:30, whilst Nuneaton is 1:00 (not on an Avanti service, so canning at quite a few stops along the way), so even with 15 minutes to get to Nuneaton from Coventry it'll be faster, making it more attractive. Also by having a different pattern of station spa means that it opens up a wider range of travel options.
It could also remove the need to change trains in Birmingham, for example being able to connect to services at Tamworth.
Of course, people will still use the existing service via Birmingham, as it would still likely leave later than the previous train and arrive earlier than the next train.