Hey beer_bosun,
Now this is not an exact science cause i'm sure you know of many traditions within the RN/RNR that have no explanation whatsoever.
My guess is that training establishments have set leave for the recruits as although you may be a recruit you still need your leave. it would be imposible for training establishments to allow them to select their own leave.
Also as they are training establishments their primary role would be to train, with the recruits on leave there is no one to train so therefore it is wise to give the staff that are involved in the training of recruits the time off too.
Feel free to add your coments if you know more than me, which you prob do. :lol: