Everyone associates ADM with just with 8U (Mites) because that is where it started, but it was designed and applicable to go all the way up to 18U and beyond. Here are the guidelines for the different age levels.
https://www.admkids.com/page/show/910488-what-is-the-american-development-model-
I believe it started around the 2009 timeframe and it was intended that it would start with the 8U and then would progress to 10U in like 2011 and 12U by 2013, etc. by the time those players who went through it in 8U got to each development level, etc. The model was to dictate the number of players on teams, number of practices, number of games teams can play, amount and focus of off-ice training, etc. 8U (Mites) was intended to be strictly in-house. Only UPMC, North Pittsburgh and RMU seemed to go with the model as associations put up more pushback. The 10U level was still designed to be primarily in-house, with balanced teams, but I do believe it included transitioning to full ice and also allowed for inter-club play.
At the same time, I don't know what stalled the initiative as everything seemed to just remain "guidelines" and were never required or formally implemented at the older ages like they were at the 8U level. I don't know if there was too much pushback from associations and the fact that not all associations are equal and perhaps could not meet all the criteria or just didn't like the model. Whatever it was, it just seems to have died. There is a part of me that believes that USA hockey kind of had to give up on it because they saw the threat of teams and players moving to AAU and if they perhaps kept pushing it and enforcing things at higher age levels it could lead more and more transition to AAU.
With the program starting in 2009 at 8U, all the players who started going through it should be moving onto college by now. I don't know where the numbers are at as far as measuring success, but I know when they implemented it they were talking about things like increasing the number of US born players in the NHL Draft - 1st round and overall, number of US players in the NHL, etc. I can't really say the model has been implemented as it was intended across all ages to be able to evaluate whether it was successful or not.
I know that when associations are to declare if they will be fielding any Tier 1 or Tier 2 teams (i.e. competing for National Championships) - there is a question on the application that asks "Is your club fully ADM compliant - Yes/No" and "If not, why not?". I think a lot of the time this is taken as "Do you have an 8U (Mite) ADM program" but I don't think that is the intention. It is more about - Do your teams have enough practices - with respective mixes of full ice/half ice/etc.? Do you limit number of games in the target ranges for respective age levels? Do you have appropriate off-ice training? Etc.
I would argue many of the programs in the area - including many fielding Tier 1 and Tier 2 teams - do not adequately meet the ADM model criteria, but this is not enforced for being able properly roster Tier 1 and Tier 2 teams.