If you do even a little bit of research on this topic, you’ll find plenty of articles practically begging you to stop using two spaces. Slate‘s Farhad Manjoo went so far as to say that it is totally, completely, utterly, and inarguably wrong.
I learned to type in the 1970s on big, heavy Royal typewriters under the instruction of the indomitable Mrs. Porter and Classical High School in Springfield, Massachusetts. We learned the double-space after period convention for all the reasons cited here in this story.
On the very day I learned that the Mac used proportional fonts and therefore no longer needed a double space, I stopped. I just stopped. It wasn’t hard, and in fact, it was good because the new way actually saved me some effort.
Now thirty years into the PC area, it shocks me to see how many manuscripts I receive from clients for their websites, brochures, and whatever — where the double-spaces still show up. Who is still teaching the kids to do this? No one in any decent public school even knows what a Selectric is!