Part of the problem here is the FMC and it's desire to get as economical a descent as possible. In the days of steam driven jets, descent planning seemed to be a knowledge of the 3 times table plus a correction for slowing down - so if I was cruising at 35000ft I'd want 105 miles to get down, and about 4-5 miles to slow down. Simple enough for most pilot's to cope with, but not the most economical descent profile. In the event that conflicting traffic prevented ATC from giving continuous descent, there was plenty of 'slack' to enable the ideal descent path to be recovered quite easily.
Now we sit staring at little TV screens, over-relying on the Flight Management Computer's calculation of best descent path (leave it as late as possible, shut the throttles and plummet towards your destination to be at 1500ft, 8 miles from touchdown doing 170kts, or whatever you amend it to) which leaves NO slack at all - apart from lobbing out the gear that is!
When flying into busy airspace - Daventry sector seems an appropriate example here - it's worth not getting too close to the Vnav (suckers?) profile, and if you are forced to by ATC, if you can, slow right down until further descent is possible - then go for it!