On a sprint weekend, the planks undergo 19 more laps of wear than at a typical event. In this case that’s almost 65 more miles of racing on the same plank. Holding the ”randomly selected cars” to the same floor allowance as if it was a standard race weekend but then NOT checking all the teams when you have a 50% failure rate is just plain wrong. Either have a different allowance on the sprint weekend, check ALL the cars or don’t check at all.
I’d double down on the reverse championship position grid and also have them race in the opposite direction so it is a completely different race for the drivers and fans.