Quite standard in Europe and like as mentioned, is just good controller technique.
We have occurences which are noted as 'technical' loss of seperation. No actual loss occurred, but seperation was no longer absolutely assured.
For example. Aircraft A Climbing through FL100, requesting FL390. In it's 12 o clock at 15 miles reciprocal is Aircraft B at FL380. The minimum lateral distance between the two is 3.6NM at closest point of crossing.
To clear Aircraft A to FL390 through Aircraft B, even though there is no hope in hell of aircraft A climbing 28,000ft in 7.5 miles, is a 'technical' loss of seperation or a seperation not assured event. We just don't do that.
I personally use the thought process that "if my screen goes dark right now, is everything safe?" and apply seperation techniques based on that ideology. It leads to safe controlling, without affecting efficiency. Sure we still do tight 6 mile crosses, rate of descent restriction descents etc, but we have a very good idea of the scenario at hand and have always assessed it as such before hand. Every 6 mile cross is not the same...sometimes we know an aircraft is about to hit a hell of a headwind, so to ensure seperation, we will turn the aircraft to get 8 or 10 miles before any lateral seperation is degraded by the headwind. It's simple but seperation assured just means make sure what you're doing is positive and effective, 100% of the time. No winging it.