As with all techniques, there will be many ways to achieve the same effect.
I have about 8,000 hours on 320/321 and 330and still use managed descent whenever I possibly can. You have to enter the most accurate estimate of what you think the descent and approach will be, i.e. make height constraints conditional where terrain permits, get rid of holds from the primary route if you think you won' do one.
Managed descent will then use the speed window to keep you on the path, if the speed drops, go direct to the next point, it is usually a change in wind/temp from forecast.
I operate this way into busy European airports as well as sleepy foreign ones and busy US/Canadian airports and it always works.
When I see pilots play the FCU boogie, it nearly always ends in an untidy descent and a gob of speedbrake - something that should be very rarely used on a 320
