There are different styles of CTR.
In the East US, CTRs are judged 100% on condition of the horse (no knot judging LOL). The speed averages out to 6.2-7.2 mph. This style of CTR is a direct descendant of the Cavalry Remount Tests run between 1913 and 1923 The first CTR was held in 1926. The original goal of these rides was to pick good cavalry horses; the ones that could get to battle in the best shape.
In Vermont, home of the oldest CTR (73 years) in the country, if you can ride a 100 mile endurance over the same course you will top ten at the speed required for the 100-mile CTR.
This is not loafing, folks! It is trot/canter almost all the way.
For scoring purposes your horse and tack can be filthy and your riding abominable. Some of us might wonder if that is what is going to create the best condition, but it is not a judged criteria.
This is the style of CTR of the organizations of ECTRA, SEDRA, UMECTRA, VTRI, AHA and OCTRA and others I have probably left out because I am tired.
The other style is NATRC which are rare back here. I have been doing the CTRs since the 70s and have not yet had the opportunity to go to the other style of CTR.