As a UK based PPL, this has proved a very interseting thread and shows, amongst other things, a lack of understanding between two halves of the same coin... commercial and GA.
I made one practice pan call to D&D whilst training for my PPL out of Rochester many years ago and it proved to me that the D&D guys were spot and and very helpful. I don't feel any great compulsion to make them everytime I fly, but will, almost certainly make another at some point soon, just to shake off the rust.
A very good friend of mine ran the D&D cell for a few years before being posted onwards within the RAF. One thing I remember him telling me about was the amount of "cramming" he was required to do on small GA airfields and farm strips to enable him to point 121.5 callers in the right direction if needed (maybe Diddley dee can confirm this?).
For any GA pilots reading this, don't be afraid to make that call, practice or for real. Usual radio etiquette applies... listen out and if no one else is on channel, make that call.
If it's a genuine one, send the boys and girls a slab or two
... they do a bloody good job for all who fly.
Happy flying