One example is creating an interface for every goddamn class I make because of “loose coupling” when in reality none of these classes are ever going to have an alternative implementation.
Sounds like you've learned the answer!
Virtual all programming principles like that should never be applied blindly in all situations. You basically need to develop taste through experience... and caring about code quality (lots of people have experience but don't give a shit what they're excreting).
Stuff like DRY and SOLID are guidelines not rules.