If I understand correctly, you would like to discourage turns where possible. I don't think what you are proposing would work with the script evaluator.
I think some functionality that might do what you want is the Global Turn Delay Evaluator. The purpose of that evaluator is to discourage turns by applying a cost penalty that makes turning more expensive. That might be your answer.
To take a step back, though, why do you want to discourage turns? Is the vehicle that is travelling too big to make many turns? If that is the case, the Global Turn Delay Evaluator seems correct.
Or are you getting routes that leave major roads and stair-steps through communities? In this case, the best answer is probably to adjust the travel times along the roads that you prefer.