The leave at 15 and return at 17 to finish Eagle requirements happened to my son. I was an ASM, and committed to the program. But my son just did not want to go to meetings any more, and went on few outings. I asked him "What gives?"
He said that when he looks around at the troop meetings, all he sees are the little kids (11 and 12 year olds) and that doing Merit Badges as a life scout is just not fun. As a 16 year old life scout, he had "been there, done that", and it did not interest him any more.
I can see that. The advancement program is geared for a 13 year old. It is challenging enough for the younger scouts, but becomes drudgery for an older scout, especially with the more bookish Eagle required merit badges (Environmental Science, Citizenship in the Community and in the World) How in the world can you make these badges fun?
He came back and did finish his Eagle required badges and project, and got his Eagle application in the day before his 18th birthday. It was a pattern well practiced in that troop. And it was the case over the tenure of several Scoutmasters for a number of years. Were our Scoutmasters poorly trained? Badly equipped, un-supervised? I think we did as well as most of the troops in the council.
This is why I have always used the layered patrol method. The NSP focuses exclusively on getting the boys trained, oriented towards Boy Scouts (away from Webelos Scouts) and has limited contact with the older boys. This gives the boys a chance to bond and develop friendships, especially if they come from differing schools. The middle layer are the regular patrols. These boys are beginning their serious trail to Eagle, working on PORs and MB's and help out with the NSP as TG, possibly PL, Instructors, etc. The NSP does not operate as a totally separate program in the troop. This layer makes up the 12-15 year old scouts. Then there's the third level, the 15-18 year old scouts that do nothing but plan adventures unique to their interests. Instead of running off only to return to get their
Eagle, they remain active, participate in leadership of the regular patrols if they wish, but generally are allowed to plan and run high adventure. These are the boys I really don't want to see at summer camp for the 5th, 6th or 7th time. Of course they would be bored.
The only way I can think this to work is the Patrol Method. Drop the NSP, and Venture patrols (HA), and what one ends up with is new scouts in with the boys wanting to do something that's not boring and instead have to teach S->FC skills for the 5th, 6th and 7th time to each new one or two boys joining up. They can't do HA as a patrol, the younger boys can't handle it so all activities are taken down to the lowest common denominator. And besides that after 3 or 4 years the boys are all mixed and mismatched that one's friends are in 2-3 different patrols.
Nope, not my cup of tea. Never liked the mixing part, just let the boys decide and it's surprising how layered their choices tend to be. Everyone's different on how they perceive this process, but for some reason it works really well for me, but then when it comes to the patrol method, I give the boys free reign. I get in a lot of nice HA trips too which is a nice perk.