It really depends on the number of passengers making the connection, the frequency of the flights, how the arriving flight is, the amount of traffic, the weather, and a thousand other things. If 25 passengers have to make a connection to Pocatello, and it is the last flight of the day, then the plane will most certainly be held, if the arriving plane is within about 45 minutes of schedule, unless there is some serious weather, ATC problem or an aircraft waiting for that gate. But, if a few people need to make a connection to LAX, and their flight arrives 2 hours late, and there is a connecting flight every hour, then the airline won't inconvience dozens of other passengers just to satisfy one. It is certainly a situation, where you won't make everyone happy. You just have to see how many people you will inconvience on each end, and to how great an extent they will be inconvienenced. To hold a plane for a few minutes can be done with a very small reason, but the reason must get progressively larger for a plane to be held progressively longer. Also remember the good old domino effect. If you are in a prime connection city, like ORD, STL, DFW or such, when one late arrival from a large aircraft, could make a bunch of other planes late, and this could keep muliplying. So, it is important to draw the line somewhere, and just stick to inconviencing as few pax as is possible. Trying to rescue a few could make many more angry.