Have someone tested friendlies in the same way? Does it worth it?
From what I 've seen so far, the development of players in old and new version is the same (I mean the algorithm and the conditions for gaining).
So I can say using the experience of training and giving friendlies in the old version, is that there is the same analogy of gaining and loosing condition (compare to training or official games).
So, now that we have logic injuries and a roster of 28 players, I can say that friendlies is a good deal.
You can get the daily 10% bonus with the X2 video and two sets (of -6,75%) , play your games and use the bench players (or put some extra greens to players-fast trainers you want to develop) vs easier opponents of course, so you can earn the green and blue packs, earn some money from the tickets and raise the moral of some players.
It's some kind of exchange of all above with few reds for a possible injury.
But now we have some stock of reds.

I can't imagine that someone can have serious conclusions from a friendly game (as in there it's a different algorithm) but I believe the new squad set up is a motive for organizing more friendlies lately.
but I would say friendlies might be useful to find the talented F-K and C-K specialists for this season.