The way that Scrivener handles spaces when selecting, copying and pasting is maybe super consistent, but it is also super annoying.
Double click on a word and it selects the word. Cut it and it takes it out leaving the spaces that surrounded it, meaning you have to have another key press to delete one.
Paste that word in between two words and you get what you asked for, but not what you wanted, the new word abuts one of the existing ones, meaning another key press to insert the missing space.
Whether we love it or hate it, Word is now the de facto word processor. Mimicking its behaviour will reduce the pain people may feel when adopting Scrivener.
Double click on a word in Word and you get the word and the following space. Paste it, either just before or just after the space between two words and you get the word inserted surrounded by exactly one space. Add it before punctuation and you get what you would expect; space, word, punctuation.
The fact that you had to add a menu item ‘Replace multiple spaces with a single space’ should have set off alarm bells that something was wrong. Guess what? Word does not need that menu item!
I know there are those that like to put two spaces after a full stop, but although that was a good thing when using a typewriter that had a monospaced font, it is unnecessary when a word processor puts an ‘m’ space after a full stop rather than the ‘n’ spaces between words.
P.S. Why oh why does a double click on a word include an adjacent double or single quote? How is that helpful?