structure in the ward.

It starts with 11 year-old scouts. If the 12-13 year old scouts are going to function properly, then they need to be First Class Scouts when they turn 12. At that point you can focus on doing 1 required merit badge a month, and run the same required ones the same months year over year. That way, not matter where a kid is, they can still get the necessary promotions. Elective merit badges should IMHO be done via Scout Camp, Pow Wow or on their own.

In wards and stakes where this program is done, there isn't any burn out, the percentage of boys making Eagle is very high and you don't have mothers earning a boy's Eagle.

One final note is that we never had a boy earning an Eagle before 14 because only one week a month was focused on merit badges. That leaves two weeks for activities that are all inclusive and a week for a service project every month.