Yes, because they are priced by First Great Western.
Cheltenham to Exeter is a shocking price because Cross Country set that flow, however as you say splitting at Bristol reduces the price to not much more than half! The fares Cheltenham-Bristol and Bristol-Exeter are set by FGW, so are more reasonable.
CrossCountry clearly want us to avoid their trains, so I try my best to do just that and use other operators where feasible.
To correct the above. Cheltenham to Exeter fares are set by FGW still. It is the insanity of the fares over different distances that cause this confusion. Saver returns valid after 08.33.
Other tickets passing through Birmingham are set by XC. On 2nd January this year the 8X restriction was removed and replaced by a 2V. In other words, when Saver returns were valid on any train after 05.00 before they are not valid till after 09.30 now.
This also includes tickets from Swindon bought at ticket offices. Please do check.
Below is an example:
Before changes Saver return Plymouth-Birmingham was £101.50
This ticket has gone up in price to £107.50 but is now not valid meaning an Anytime is now required. Cost £213!
Penzance to Edinburgh is £423. Only £27 less than a 7 day All Line Rover!
However, if you are going to Scotland from Totnes northwards buy a Saver return to Glasgow Any Permitted. It is valid and is much less than £360 for the Anytime Return to Edinburgh.
Definitely worth splitting tickets with distance.