How to go about making and organizing scripts that you only use once.

Hi there. I'm entering a coding problem where I've gotten quite good at making tools, modular code and components, similar to what Unity provides, but the problem I'm facing now is that it's a lot of work creating scripts that I need for very specific situations whilst also making sure that code is modular and has other potential use cases.

The fix to that is to make one off, trash scripts that I'll only use once in the game. But I really don't like that approach as I have to treat the trash script as a public class with a specific name and such, which gives a wrong idea of what that script is supposed to be, a one off, one use logic trash bin. I'm guessing this is one of the flaws of OOP, that you're encouraged and expected to write in a modular fashion, so when you don't, it's awkward and disorganized.

Am I understanding this problem correctly and what are the standard ways of going about this problem? Thank you in advance.