On the other hand most modern educational theorists believe one learns more from doing than from observing. Schools are structuring away from observing and taking in information from an instructor (lecture) and moving more towards those that use a more practical, activity based approach like EDGE which will gain adherence to the subject matter faster and retain it longer.
This is why I still champion the level playing field of the NSP for the new boys in the program. They are not just there to observe, but even in Cub Scouts were able to experience a bit of "running the show" as a denner for a short period of time. Why when they get to Boy Scouts is that process put on hold for 2-3 years until they have observed long enough, or at least had the older boys age out and reduce the competition for the leadership positions.
This is why we hear about so many SM's having to mandate that certain scouts be in advancement POR's so they can move on to the next rank, and yet complain loudly that the boys don't or even can't function because they have in fact no experience in the position.
Keeping the numbers low in the patrols insures the opportunity to learn best suits the learner. If 8 boys is too much for the NSP patrol structure, push for 6 if possible. The boys should be given the best opportunity to be successful and that does not mean postpone their practical experiences to sitting and observing. It means give it a try and mentor (TG and maybe the PL if not a new scout) towards success. Should the TG be mentoring the new boys? or doing it for them? Same for the PL? Is he to be their just their leader or does he have a responsibility to mentor and develop his replacement from within the group?
Boy quit scouts the first year for a variety of different reasons. Scouting is not for them. They like the arts and crafts, but going out into the woods is a whole different thing. Parents are burned out and drop out. Everyone else gets to do things and I have to sit and learn to tie knots while the other guys are having fun DOING things. To boys at this age, learning scoutcraft skills isn't doing the adventure that they thought they were going to get in the first place.
Everyone puts an enormous amount of energy into making Webelos II a transition into Boy Scouts, but it's not Boy Scouts. The NSP finishes the transition because now it's supposed to be for real Boy Scouts.
Keep the patrols small, keep everyone active and doing POR within the patrols from PL to APL to QM to Scribe, etc. GBB's patrol method training has everyone working, no one is observing older boys.
For 1-2 years Little Johnny sat around tying knots, cooking meals, setting up tents, lashing poles, doing first aid, and now that he's First Class, he needs to do a POR. Good luck with that. If he happened to have a good PL he might do alright, but if one hasn't done it before, it makes for an intense learning curve of high expectations.
Having the boys lead small groups of 5-6 boys, make your mistakes there, that by the time one gets to FC, they at least have experience in what to do. This is why the patrol method is so important to the boy's learning of leadership.
I have never gained experience in anything in life by sitting around watching other people do things.