1.The spot of the ball must be correct.
2.The ball must not be moving at the time of the first touch/kick.
3.The required 10 yards must be given.
It is rare that the above occur in time for a "quick" kick in youth soccer. The decision to hold the kick depends on the referee and his/her ability or desire to ensure the above 3 conditions exist. The referee should not hold the kick to allow a wall to be set up. An effective wall might be the result of the delay, but not the reason for the delay. An experienced referee may allow what appears to be a quick kick if the defending team intentionally uses the 10 yard rule to delay the free kick. If the free kick hits an opponent who was not giving the 10 yards, the ref might have the kick retaken. If, on the other hand, the attacking team gains an advantage on a quick kick, the referee may let it go if the defending team is infringing on the 10 yards.
If a team uses delaying tactics when defending a free kick it is a great time to send the first touch wide or drop the ball back and kick it over the wall. Many times the defenders are not marking up because they are screwing around with the wall.