My first saltwater tank was a 10gal mixed reef I got from my brother because he went off to school. I did no research and just half-assed took care of it. I had it for over 2 years and topped off with distilled water whenever the water level got 1" below the top, and only did 2 water changes in those 2 years. The water changes were with distilled water and oceanic salt mixed in a jug, then dumped right into the tank while still cloudy. I never had a single fish or coral die. I had a remora nano skimmer on the tank, but it really didn't pull much out. I might have emptied the cup every couple months. I was a bad tank daddy.
These days on my 55gal I do a 5-10gal water change once a month, or whenever I can be bothered to mess with it. Not sure why though, it seems all my LPS 'puff' up more after a couple weeks without water changes. I guess I do it because I don't dose or test anything, and just want to hopefully replace any trace elements lost in the months time with whatever is in fresh saltwater.