In reply to Mark Kemball:
The criteria it uses are:
- Routes that you haven't already logged or added to wishlist
- 3 star routes
- same grade
- same county
If this returns more than one route, one if them is chosen from random to be the route of interest. Theres potentially some flaws in this approach (ie only selecting 3 star routes), but it was just meant to act as a way to find routes "nearby" that are good and presumably within your capabilities.