I was thinking about the various distances that people would race and how their specialities would affect how they do in this test?
A person specialising in 60 minute time trials would do better in this test than the same person who specialised in Long stage races, assuming his potential ability in both was similar.
If the test can be applied to correlate to hill running climbing potential is probably a question for a hill running forum although the 1 hour basis is average for hill races here.
What you are getting at is more the power profile of a rider which is done by testing 5 s, 1 min, 5 min, and at functional threshold power (see here for more details.
However its not so much 1hr versus longer. A 1 hr time trial will predict performances rather well at longer event. 1 hr is long in bike testing.
Consider a 180km IM bike leg, people typically race it at 75% of FTP, a 20km sprint bike leg would be at or over 100%FTP. So a five hour IM biker versus a 30 minute sprint biker, which one would do better at this test? The one with the higher FTP. FTP is a measure of aerobic not anerobic hence the 5min TT to burn out the legs.