Extracts tend to be really strong, concentrated flavors, and they can be over-powering if too much is used. I'd suggest adding extract in recipes more to taste, not as a full on substitute. If you do try using extract as a sub, use half (or less) of the amount called for in directions. For example, if you need 2 tablespoons of orange zest, I'd use less than 1 tablespoon of orange extract.