I think it`s a great idea.
The Nadeo Tracks are not bad, but as you say they are very conservative.
And there are a lot of Tricks, you don`t learn like:
Full Speed Drift
Dirt Challenges
Special Jumps (with a speed limit, unusual angle etc.)
Landing Challenges (on a special point or `drift landings`
Unusual Blockusing
High Jumps or High drops
I think the time of the Track should be between 10 and 30 sec. and the Goal or the Trick should be clear.
I will make a Track and post it here maybe its gonna be fun.
Maybe someone can post some ideas, which Tricks should be involved.
The Goal should be to get Training levels for new players(or anyone who likes short Tracks)