Myself and Mrs J fly often (Mrs J 55 flights in 18 months) all over the world and I can count on one hand the number of flights that have flown to the schedule.
None of the flights have been with any of the low cost airlines. Worst was a recent BA flight that was 2 hours late because a tug wasn't available so take off slot
missed and next one was 90 mins later!
Just a sign of the time I'm afraid and only going to get worse. No changes to the rules regarding time keep will make any difference.