From own experience, the latest (in the day) a flight is (especially the short 2-3h flights within EU) the more chances is you will be delayed (if every fight i

From own experience, the latest (in the day) a flight is (especially the short 2-3h flights within EU) the more chances is you will be delayed (if every fight is delayed by 30mins, by the end of the day multiple those 30mins x 4 or 5 or 6). When a company may see that "oops we are gonna be paying $$$$ for the delays" they will have no fear to bring in another plane (not the one you booked). The same applies of course for any planes that are damaged, etc. I tried asking ChatGPT but couldn't give me an answer of the frequency "how often to air companies swap the planes" (I tried with various choices of words) and it couldn't give me a percentage or any other metric.