I have done many different types of fish. Arowana, Plecos, catfish, Wild Discus, Domestic discus...etc..etc.
Discus is the only fish that has this attached to it, "So where is the butcher, so I can get beef heart". I have seen people buy discus and then make their way to try and find beef heart right after (which is not that easy to find). Its automatic. I am going to get shot down by some for saying it, but its true. Arowana people don't go buy beef heart, nor do people that buy large predatory fish. Who buys some pirhanna, and then says lets feed beef heart or steak! Yet discus has this beef heart thing to them, feed them allot myth to them. Discus are some of the most adaptable fish I have ever had. They eat everything. You could throw hot dogs and they would eat it I bet.
The reason I think there is this thought you need to do allot of water changes...well, back in the day lets say in the 1970s/80s when people started creating domesticated discus and feeding beef heart..well, guess what happened? Their water got funky fast. Really fast. Especially since they were probably throwing down food 3-4 times a day. Maybe even more. These guys like Jack Wattley were the fathers of making discus a major hobby, and then this rep just kept on going and going. So the WC thing got big. I know a guy who does WC 2-3 times a day! and yet feeds BF 3-4 times a day! - there is a connection...
But let me make this clear, if you want to feed beef heart. Cool. Its your fish to enjoy and if you don't mind doing WC, go for it. Whatever works for you.
I have had discus for years, I do WC maybe once a week. I don't do beef heart. I usually make a seafood mix, feed that once a while...and just feed NLS bits or Tropical discus dry food. I feed 2x a day. You can even cut it down to 1x when they are larger. Its more healthy for the fish I find. Its fine, they don't die. They can go without food for weeks.
Anyways, please don't shoot me about the BF comments.