I agree that punctuality is an issue for 12235, but it still manages to run with acceptable delays upto 2-3 hrs despite of congested slots in NCR.
But 12236 runs with awesome priority enroute, because it's part of the evening Rajdhani gang. It's one of the most punctual trains to Patna, because it runs back to back with Patna Rajdhani. They have similar runs, but anyways Rajdhani is a Rajdhani.