Ok actual example:
yesterday I was dropping someone off at Cranfield. On the return I contacted Coventry Radar for a service and heard the following:
Coventry Radar, G-XXXX C152 from XX going to XX VFR 2000 1018 request basic service.
G-XXXX that is far too much information for the first transmission, Callsign only on first contact
Its not sloppy RT to use just callsign, its just a different approach that some controllers prefer.
Nick