For my family, just our normal eating habits result in saving money over having the dining plan. Our way of eating is similar to what's already been mentioned above:
*We don't like to wait for breakfast, so we keep breakfast items in the room, eliminating the need to buy one Disney meal.
*We tend to be "grazers", so we opt to keep snacks in our bag that we eat here and there, which cuts down on how many snacks we buy in park. We also often buy small portions of food when we do stop for something to eat. (I love kid meals at counter service places because I like getting a water and also some clementines as a side as opposed to the chips and fries that often come with adult meals, too.

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*We are big water drinkers to begin with, so coupled with the extra hydration needs of a Disney trip, we drink a ton of water, which can save money if you might often opt for specialty or alcoholic drinks.
*In non-pandemic days we are big on sharing. None of us are accustomed to eating a lot of sweets, so if someone wants to try a particular treat, we will buy one and share it among us, or if possible, pack some into a ziploc to finish later. And even with savory snacks, if we all wish to try a few, it still works out better to buy one each and cut it in 3 or 4 pieces, than to buy 3 or 4 and then find that we're getting too full to finish them all individually. This is particularly true in Epcot, and even more so when there's a festival happening.
*Because one of us is not big on the waiting involved with table service restaurants and one of us sees any time eating as time not spent on rides, we tend to go more more quick serve places, which cost less. It's also often easier to get less food that way--you can buy side dishes or again, a child's meal, very easily. I personally love a place where I can get a side salad and some fruit instead of a full meal at lunch. So cool and refreshing.
*Lastly, some of us are vegetarian/vegan, and the plant-based meals, while not ALWAYS less than their meat counterparts, are still often less.

*Lastly, we find that during the year people sometimes ask for ideas for gifts for our family, and depending on the situation, we might suggest Disney gift cards. Our kids love having a way to buy their own snacks as they go along, and a card can be a good budgeting tool for them. They can see the total decreasing and know to be careful in their decisions about their snacks.

And if a card is given to us as a family gift, then we can use it to cover a few meals depending on the meal and the card amount.
