Every time I see another thread about sequencing bitching from the sky gods, I doe a little more inside. It is all pretty simple yet so complex and is a game of seconds.
Assuming a non arrivals manager type program (eg Meastro), the arrivals guy from the North gets a rate he has to give the approach guy, the guy from the South a rate (directions may vary) and then the appproach guy catches them. The arrivals guys make those rates happen however they can. Speed ups for number one then varying degrees of slow down for everyone else. The approach guy then has to put these two (or three or more) streams on the runway. This means that perhaps the number one from the North may not be number one for the runway and hence, has to slow down after going fast..... and vice versa from the South who was number two there but is now number two to the runway beating number one from the other end....
Now, for an arrivals manager type program (eg Meastro) throw in crews who are too retarded to do what is asked of them and magnify the above.....
... but you already knew this,...... right?