Is there something here about the role of (and lack of in this case) deliberate and intentional practice?

4.2 hours a week in a car doesn't imply that any of that time is spent doing things that may make one a better driver (by whatever standard we're measuring this), it's just repetion of the minimal amount of driving skill that's enough to get you by.

If it's not possible to increase one's skill in anything without practicing things that are just on the edge of capability then no amount of regular, unsupervisied driving without any critique targeted towards improvement is going to help.