On a visit to NATS last year we visited the D&D room. The RAF sergeant on duty asked us to do more practice pans and training fixes as 1) it gives the guys in D&D more practice and 2) he was concerned that people further up the command chain were concerned at the declining number of calls, thus calling into question the need for such a service if it is not being fully utilised. As a low hours PPL I want to practice talking to the "real deal", not my friendly instructor sitting next to me.