Howdy and welcome to the club!
I'll be honest here and say that I only do about a 15-20% water change in my 28g Nano every month AND I don't dose or supplement anything. ALL my good frags and corals are in this tank and do awesome. I have everything from SPS, LPS and softies. My SPS has actually grown more quickly than my other frags. I probably don't get the growth I could if I did more water changes, but still...haven't had any issues with keeping things happy for the most part. Lots of factors, but a stable and established tank is probably the most important. IMHO