Which of the following may not be the reason that some plane will always be late landing or tak-ing-off?

W: Nigel Linge is editor of Business Travel Weekly. Nigel, thanks for being on the show. Now, what kind of problems do airline passengers face nowadays?
M: Well, most of the problems are caused by the heavy volume of traffic. You know, all airports have a limit to the number of take-offs and landings they can handle.
W: So what seems to be the problem?
M: All flights from a busy airport arrive and leave at more or less the same time. If 60 aircraft are scheduled to take off between 5 p. m. and 5: 15, and the airport can only handle 120 an hour, that means some will always be late landing or taking-off. And if the weather is bad, oh, you can imagine what the situation is like. So passengers have to be loaded into each plane, and then the planes have to line up to take off.
W: So waiting at the lounge or on the plane is quite common.
M: Certainly. And another problem that’s very common is overbooking. Quite often you hear an announcement on the airport loudspeakers: "We have oversold on this flight and would like volunteers to go on the next flight out. " If you decide to volunteer, you may get a cash bribe or free-trip voucher, but make sure you get a guaranteed seat on the next flight and a free phone call to whoever is meeting you on the other end. And worse still, you arrive with confirmed reservation and you discover you’ve been bumped off the flight.
W: So, what advice would you give to business travelers?
M: I’d say "Avoid big airports if you can". The reason is there are too many flights there. Then, remember not to check your baggage if you can help it. Another thing is " Be prepared for delays" Take something to eat and drink in your hand luggage.
W: Nigel, what kind of mistakes do inexperienced travelers make?
M: The first mistake business travelers make is to take far too much luggage. Remember, take only carry-on luggage, because at most airports, you can get away with two small bags.
W: Oh. I see.
M: Another mistake people make is to think that you have to pay full price for air tickets. You should find out about the different ticket options. For example, an RTW fare can save up to 40% on normal fare.
W: Excuse me, what is RTW?
M: Round the World. For example, if you’re going to Australia from the USA, you could go out via Singapore, and come back via North America.
W: Oh, that’s very useful information.
M: And another mistake is to go away for too long. Most people’s efficiency and energy start to fall off after two weeks away. So my advice is "Keep your trip short" , only go for two weeks and never for a longer than three. Another point is " Don’t expect everything to go according to plan". You need to learn to expect the unexpected.
W: Yeah, this is something travelers have to remember when they plan their trips.
M: And another thing, get to know a good travel agent and make sure he gives you the best possible service. Take discounts for example, a good travel agent can get first-class ticket for the price of business-class. This is because he does enough volume of business and he can get discounts with airlines on his own behalf. He should pass them on to you. So make sure he indeed does.
W: I think the worst part of a trip is having to travel overnight or being stuck for a weekend in some dreadful place. Are there any ways avoiding that?
M: Yes. We can break or stop over in a more relaxing or lively place. It’s often available at special cheap weekend rate. Various airlines and hotel chains offer these. And it’s always more pleasant to stay a night in a hotel than on a plane even if you travel business-class.
W: Yes. OK, thank you, Nigel, for all the useful information and advice.
M: Pleasure!