Is it good to use @extend everywhere?

Question

css

Is it good to use @extend everywhere...
There are 5 types of buttons on a large project:

.btn{
    .....
    &-black{
        ....
    }
    &-white{
        ....
    }
    &-orange{
        ....
    }
}

How and why is it better to do it, create a class for each button and throw styles as an extend, or is it better to write classes?

Answer 1

@extendneeded for different classes and placeholders.
For example, if you have the same block border design for the header and footer.
Here, just a different colorization of the same buttons. Everything has already been done correctly and @extendin this case is not required.