Have you come across many examples of ‘exemplary’?
No, not really. Mostly with senior NCOs having completed 21/22 years. The grading and pen picture appeared in the soldier's AF B2067 (character reference) which was given to him on discharge. Only the grading was recorded on his AF B268 (Proceedings on Discharge) or AF B2056 (Proceedings on Transfer to 1st Class Army Reserve) - which ever was applicable - and these are the most likely documents which we will encounter in our research.
My great grandfather left the Regular Army with his LS&GC as a Colour Sergeant after 22 years but was only graded very good. He then went on to serve on the permanent staff of a Volunteer Rifle Regiment as RSM after which he was graded excellent. Not that it was much use to him as he didn't need to look for a civilian job when he left because he had a reasonable pension after 37 year's service.