Mariechen M. answered 06/20/19
NJ Certified Teacher Makes Learning Fun and Productive
Hi! When I researched this I found out that the em dash shouldn't appear more than two times per sentence. It can also take the place of commas, parenthesis or colons. It says that an em dash replaces commas to enhance readability or to really emphasize something. For parenthesis, it says that em dashes are less formal and will draw more attention to the words. As far as replacing it for the colon, it says that em dashes are good to draw attention to a conclusion because they're less formal.
I hope this helps you!