That's great when you have the 'knowledge' so you can program it all in before the descent, but when you come in on a Bovingdon into LHR, they fire at you new instructions like FLXXX XXnm before BNN. Sometimes it's easier to just use your descent line to overlay the end descent point using VS so you can monitor outside better rather than be head in reprogramming.
I have a suspicion controllers 'speak with forked tongue' sometimes, as in "you can slow down now because they're holding ahead". Coming in from AMS direction low on fuel once, they told us that (20 minute delays) and we asked to absorb the holding delay en route and slow right down to minimum speed. Took forever to get to LAM. Switched frequency just before we got there to be told to enter hold for 20 minutes. Protestations brushed off with "I don't know anything about that!", and so we held as well. Now when I hear '20 minute holds and you can slow down', I reckon the timer works from when you enter the hold so all slowing down early does is delay you even more! Gets me going even faster.