In thinking his duties as a naval officer probly wasn’t the normal gig wouldn’t you agree? What with being a royal and all.
On the contrary, as with his sons, in his service he was given no special treatment. By all accounts his performance in post was OK. He didn’t see active conflict: but that was only because the UK wasn’t involved in any significant conflict during those years.
Military service apart, he has spent most of his adult life actively heading a large and successful agricultural and property business, the Duchy Estate, which provides his own income on which he pays tax at the highest rate.