Sandpaper Question

I probably use a piece of fine-grit sandpaper longer than I should, till it doesn't feel rough at all to the touch.

I have also tried using coffee fiters for that kind of fine-grit surface polishing, too.  I haven't been able to tell much of a difference, but it did help to remove or rub out bits of dust that had adhered to a painted surface while the paint dried and cured.

I will usually replace when the paint loads up in the paper. That's pretty often though.