Over the years I have received many MCT queries for the Ask Alex column.
For someone who spent some years in the travel trade I have always understood that MCTs are based on airline schedules as displayed by OAG or by airline booking systems, timetables and so on.
It has to be that way, otherwise how can network carriers plan their global schedules ?
But of course as the above examples have shown, MCTs are easily undone by events on the day of travel. For example, strong winds this morning at Dublin mean that connecting flights from the UK mainland are having to be delayed or diverted and this will mean that hundreds of passengers will miss their (transatlantic) connections.
If travelling on a through ticket then an IATA airline is obliged to look after you and honour the onward flight booking even though you may be travelling on a restricted ticket.