I'm going to share a potentially unpopular opinion about the planning of most European teams in important tournaments.
If we go back and look at the way European teams managed their presence in international competitions, we can see that they don't take it very seriously. During the past VNLs, we could watch several prospects being tested but NEVER making to the main roster. As a matter of example, look at the [countless] outside hitters we've watched from Turkey, Russia and Italy in these past years...
Also, we can see that European teams often rest players that, in my opinion, are not that good to be granted some sort of rest. What's the point of resting Egonu in important competitions such as the VNL? She's a 22-year-old girl who never won anything meaningful with the Italian NT. The result is this: she's used to winning matches of the European championship, playing well in a super team like Conegliano, but totally disconnected from her NT after a 3 months absence from actually playing. I won't even mention how crazy it is to rest players like Fahr, Danesi, Caterina, Pietrini... As a Brazilian, this is even crazier for me because I remember that Fabiana and Sheilla were first invited to the main NT in 2003 and got to rest in 2015 - after 12 years of service! They got to rest as established players, perhaps considered as the best in their positions.
I am saying all of this just to make a point: I don't see continuity in the work of most European teams, and teams are built through the years and not after training in a 3-month bubble.
Every year we get to see a completely different roster from most European teams... Players are invited and then disappear, many get to rest and then they are invited back out of nowhere. That's why I think the USA and Brazil, despite not having the best players individually, have always shown a more balanced game. This is the result of forcing their best players to participate in training and important competitions, and I think super young NTs such as Italy should adopt this strategy as well. Team building is not about taking players that did a great season and putting them together to train [and sometimes not even that], but it's about creating a team out of a roster.