The textbook answer is to replace the winch handles in the pocket when not in use.I know they lock in but I don't think the winch handle looks good just sitting there so we remove it.
Once set, we tend not to trim and retrim the way racers might. So I could see them leaving it there.
You are correct cruisers do not spend a great deal of time trimming after the sails are set. Aesthetics aside, he winch handles can be a tripping hazard and they make it difficult to unload the winch. After sheeting in, the handle can be put into the pocket carefully without going overboard.
On a race boat, the winch handles are left in place. They tend to have many more of them, plus a few spares. Last year while crewing in Swiftsure with some other instructors, we kept having to remind them to leave the handles in place. It was really against their nature to do so.