New features: Track Usage and Track Progression

I found nothing in the manual about it. Could someone explain to me these new features and the recommended configuration? Thank you.

 

These are about the new dynamic track conditions:
- track usage : this sets the starting point, from a clean race track to an already used one with a rubbered racing line and marbles outside
- track progression: how fast the track changes
The settings are more a personal preference: select Max track usage and you will see the end result in a way. Same with a fast track progression: you will better see the rubber appear.
The manual is still WIP btw…

 

Thanks for explanation.