Bu what do you really learn when you play 8 or 9 youngsters? I think it is overkill and you learn nothing. There isn't a youth team in the world with 8 or 9 youngsters with a genuine prospect of stardom. Each youth team has one or two, or, if you are lucky, three players who MIGHT make the grade. They are the players who probably already stand out amongst their peers and you now need to see how they respond to the added pressure of being played alongside players who have already set the standard.Play those two or three prospects with their peers and they will still be in a position where they feel they are the superior players and will play with that level of confidence. What you want to assess, to a certain extent, is whether they can demonstrate a similar degree of confidence and assurance when they are a small fish.
i.e. Will Kakuta take a man on or will he always look to play the ball to Lampard? Will Sturridge shoot from 30 yards or will he always try and play in Drogba?
I accept this is a somewhat simplified argument but the overall point should be clear.