If you ever feel like you should put two spaces after periods when turning in copy, stop that feeling.
Don’t do that. Just don’t.
Every Editor Ever.
God, yes. I don’t…
It used to be correct usage for submitted manuscripts, back in the day: the way to make sure that the typesetter would recognize the end of a sentence. Later the convention started going out of vogue as more and more ms’s were the product of wordprocessing, and more and more novels started to go to the publisher in electronic form, bypassing old-fashioned typesetting.
I still do it about half the time. Old habits die hard…
Oh wow that’s what I was specifically taught in school.