I think you play too many singles in your decks. Generally having most cards in pairs makes the decks more consistent. If you have a look at decks played in Mythic they all have a high number of cards in pairs.

This is especially true for decks that depend on finding specific cards during mulligan, like Food Chain. This is because when you send a card back during mulligan, the game removes its other copy from the pool of cards available to show you next - the logic being if your not interested in card x and you reject it, it doesn't make sense to show you the second copy of card x again during mulligan.

The consequence of this is that with lots of doubles, the pool of individual cards the game is going to show you during mulligan is smaller than if you have all singles. A deck full of singles has 30 different card types; a deck full of pairs has 15 different card types.

If your deck is full of singles and you send 1 card away during mulligan, the game will pick the next card to show you from the

30 different cards in your deck,
minus 3 cards shown to you during mulligan,
minus the card you sent away,

which means there are 26 different cards to chose from.

If your deck is full of pairs and you send 1 card away during mulligan, the game will pick the next card to show you from the

30 different cards in your deck,
minus 3 cards shown to you during mulligan,
minus the card you sent away,
minus its other copy (it could also be in the mulligan list though)

which means there are 25 different cards to chose from. In this case - if you don't have repeated cards in the initial mulligan, every time you send a card away you remove 2 cards from the list of possibilities instead of just 1. This makes it more likely to find the card you are looking for because there are less options to chose from.