I'll chime in a little from the Czech perspective (which could very well be VERY different from the Swedish one).
We are in all those tourneys every year. BUT... we got silver at Hlinka and then 80% of our roster left for CHL. So we are sending C and D teams to those tourneys. It's a lot of games but not many guys made the final roster. In fact, our final roster hasn't played together (mostly) since last August at the Hlinka.
USNDTP (which I love) are the same guys together all season. Belarus has something similar. I wish the Czechs would adpot it.
But, I don't see much value in a November U18 tournament where the Czechs have maybe 3 guys that will make the final cut (Benak, Jiricek would've and then it thins out fast).
Our U17 and U16 look very strong and I guarantee a lot of them will be gone after Hlinka too! Hard to sustain momentum.