Canterbury won 13's , 14's and 15's SI Tournaments. And those sides could have been missing their "better" players at NTC. 13's final was the 2 Canterbury sides. All those sides have a heap of FTC players in them.
FTC includes selections to trial from the clubs respective FDO's, ie Gareth, Fred, Tetso etc.
TOL happens at a few different times during the year, and also used to help determine NTC.
You'll never get the best x number together at one time. The first thing is they are children, the second different coaches see differnet things, and thirdly it's hard to find an unbiased player evaluation.