language agnostic - Code Reusability: Is it worth it?

Question

We all write reusable classes and code.

We factor in configurability to allow us to reuse this fantastic new class again and again.

We tell our bosses that spending this extra time now will save us time and money later.

But in reality, for those of us who don't write third party libraries, and spend our time working on a application as a whole, how many times does that one class you spent extra time writing to be reused actually get reused in another project?

How many bespoke classes do you have in your library which will get used in more than one project?

Answer 1

My common rule of thumb is:

1. If you repeat it once, copy it.
2. If you repeat it twice, refactor it.