Hi Jimmyg, descent speeds, holds ands spacing is ,well, a complex issue involving several ATC agencies.
But if we stick to the discussion at hand (overshoots) I can give you an example. Say you're no 1 and I've got someone fast behind you (eg a freighter) whom I've squeezed in front of no 3, and I'd like you to do 180 kts to 3 miles to make this thing work, well, odds are you may not (be allowed to) do it. So somebody will go around. If left to your own devices, you probably could hand fly your 777 to 3 at 180.
At our end, there are controllers from at least 15 different countries, and although we all work pretty well the same, we all have differing styles. Some are more 'pilot oriented' than others. I'm sure you'll figure out on the frequency those who are more 'concerned' about your issues: feedback on where you're being vectored to, distances to go, required speeds, traffic to follow, etc.
The key really is more interacton between the two groups.