Let me try and put things into perspective for you guys. You can cite all the ICAO references you want, but the following is a reality check:
Busy night, DESDI and BUBIN holds full. DXB has one approach controller, he feeds one director. One landing runway. You need the aircraft to exit each hold 20 miles in trail in order to have them land 5 miles apart. Therefore an aircraft can exit each hold every 5 min. (250 kts = 4 miles/min)
The guys working the holds are in Abu Dhabi Center. One controller each side, but they're also busy working traffic entering the holds, overflying, sidestepping into Sharja, etc etc. Doubtful that they have time to calculate a nice EAC time for each aircraft while you're still 20 min from BUBIN, although that would be nice, now wouldn't it. They're just too busy. ALSO. in the interest of fairness and efficiency, if traffic becomes 'lop-sided' (say light at DESDI and very heavy at BUBIN) we at DXB might call up and say "OK, space them 30 at DESDI and 10 at BUBIN, at which point all the EAC times go out the window. Even an overshoot causes extended vectors for all concerned, there goes your ETA! And because 80% of the traffic is heavies, you can't jam them like back home, wake turbulence separation must be respected.
Guess the point is we're quite low-tech, relying on some very good people to make it all work. We do not have some of the fancy flight management software available in other places. Another yet another factor is that a very high percentage of traffic here is long haul, where fuel is critical, thus this discussion.
Hope this helps a bit.