it'l be interesting to see PDR having a go this weekend,
but he's never driven the 2017 car... whats the point in having a reserve driver thats never driven the car?
you'd have thought they'd have given him the odd practice session now and again
They are probably not allowed to for cost-cutting reasons. Otherwise, the teams would take the mickey and be using these training days for development testing.
I would imagine there could be an argument made that for safety reasons, reserve drivers should have a certain number of hours in the car if you are going to drive the car in a race.