I would think it's because your time of service will be proportionally shorter and some of that will be taken by your formation in your chosen trade (The years of subsidized education are counted to determine how many years you have to serve after your studies).
Other than that, going for the TAD, Medical and Interview tomorrow, in order to be merit listed for the March 15 selection. Applying for Arty (1), INT O. (Closed) and INF (3), I hope I get in haha! Going the civvy route, because my marks are apparently too low for RMC.
Good luck to all!