Give a response by comparing 2 times (in different columns)

I have a sheet which has a dispatch and arrival time in 2 separate columns. Our response time should be no more than 1 hour during office hours (7 AM until 1 AM).
Between 1 AM and 6 AM our response time has an additional 1.5 hours travelling time.

I am trying to extract data which shows whether or not we have achieved these time frames as a percentage and highlighting those jobs we do not manage to meet within time.

I have tried using the decimal value of a time but have found these to be unreliable as several different decimal values for the same time are shown.

Any ideas anyone please?