1. A machine-readable storage medium encoded with instructions that, when executed by one or more processors, cause the processor to carry out a process for generating directions for use in navigation during a current driving session, the process comprising: receiving a target destination; generating at least one candidate route; probabilistically determining that one of a plurality of conditional variant models associated with a target attribute corresponds to a condition of the target attribute, the plurality conditional variant models learned from previous user driving sessions; and scoring the at least one candidate route using the determined conditional variant model; and providing a scored route to a user.